The hammer rang once. A spark jumped off the anvil and did not go out. It waited. They followed.

Inkling was eleven now, and she did not believe in sparks that waited. She believed in things she could write down. She had a notebook in her coat pocket for exactly that reason, a small square one with a green cover, and the first page said, in her best handwriting: Things I Noticed.

She noticed that the spark was the colour of an orange peel held up to a window. She noticed that it did not flicker. She noticed that when she took one step toward it, it moved one step away, down the lane that left the Green on its eastern side and became, after the last house, the road to the Slow Lake.

She wrote all of that down. Then she followed it.

The road to the Slow Lake was the kind of road that takes longer than it should. It went round hills it could have gone over. It stopped for bridges that were barely needed. Inkling had walked it many times when she was eight, on her way to Sir Pinwell's library, and she had always thought it was a road that wanted you to slow down before you arrived.

At the top of the last hill she could see the lake. It lay in the valley like a dropped mirror, flat and silver, with the village tucked against its near shore. There was the library, three floors tall, the tallest building after the bakery. There was the bakery itself, with its crooked chimney. And there, on the far side of the green where the village kept its market, was the long low hall with the chequered roof tiles. Captain Castle's academy.

The spark drifted down the hill and settled on the academy's door knocker, a brass rook polished bright by a great many hands.

Inkling's grandmother had given her a chessboard when she was six. It was a folding wooden one with a hinge that squeaked, and the pieces lived in a velvet bag that smelled of cedar. Her grandmother had taught her how the pieces moved and then said, "That's the easy part. The hard part is knowing why." Inkling had been trying to work out the why ever since.

She lifted the brass rook and knocked.

The hall was full of children and noise. Some of them were playing at the long tables down the sides. Some of them were not playing at all, but were arguing about a game that had already finished. At the front of the hall stood a chessboard so large that each square was the size of a dinner plate, with pieces as tall as Inkling's knee.

On a stool beside the big board sat Captain Castle.

He was a rook, as anyone could see: square-shouldered and solid, with brass buttons on his waistcoat that were slightly too large and a small dent on his left flank. He had been a great player once, the children said. Now he taught. He watched the noisy hall with the patient face of somebody who has been an adult around children for a very long time.

When he saw Inkling in the doorway, he raised one hand.

"Ah," said Captain Castle. "The girl who named the pin. Come in, come in. Take your time. The board will wait."

Inkling's ears went warm. She had not known that anyone except Sir Pinwell remembered that. When she was eight she had pulled a stuck book out of the library shelves and asked why it would not come out, and Sir Pinwell had written the word pin in his notebook because of her. She had felt very proud of that, for about three years.

The Captain clapped twice. The hall did not go quiet, exactly, but it went less loud.

"Next week is Lantern Night," said Captain Castle, "and the academy is putting on a show. Not a play. A game. We are going to re-stage the most famous teaching game ever played, move by move, on this board, with the whole village watching." He looked round at them. "It was played in Paris, in a box at the opera, a very long time ago. It is called the Opera Game."

A murmur went round the tables. Somebody said "What's an opera?" and somebody else said "Singing, but longer."

"Here is the trick," said the Captain. "Every move that matters in this game belongs to somebody. A pin belongs to Sir Pinwell. A double attack belongs to Captain Crossfire. And so on. When their move comes, they will step up and play it. But they need someone to call them. Someone who watches the board and works out, each time, who should come next."

He turned his head slowly, the way rooks do, and looked at Inkling.

"A prompter," said Captain Castle. "Somebody who notices things. Would you like the job?"

Inkling had a great many feelings at once. She felt chosen, which was lovely. She felt watched, which was not. And underneath both of them she felt something sharp and eager, like the moment before you open a parcel.

"Yes," said Inkling. "I'd love to. I already know some of the names."

"Good," said the Captain. "But knowing a name is not the same as knowing when to say it. Remember that."

She wrote it down. Knowing a name is not the same as knowing when to say it. She underlined when.

Then the Captain introduced the faculty, one at a time, because a prompter has to know who she is calling.

Sir Pinwell she knew already. He sat at the end of the front bench with his notebook on his knee and nodded to her very slightly, the way you nod to someone across a library.

"You will call me for pins," said Sir Pinwell. "One line. Hold it. That is all I do."

Next to him, taking up a great deal of the bench, was Captain Crossfire, who had not yet arrived and was therefore represented by his hat.

"He is coming on Wednesday," said Captain Castle. "You will hear him before you see him."

Then there were the twins, Gable and Garrett, two walking towers who stood at the back of the hall because they did not fit on the benches.

"One of us goes first—" said Gable.

"—and the other comes behind," said Garrett.

"Straight lines only," said Gable. "We don't do diagonals. They make us dizzy."

"Open file, open road," said Garrett.

In the corner by the stove sat a lean stoat in a travelling cloak, with his legs crossed and a cup of tea balanced on one knee. He rose and gave Inkling a small, courteous bow.

"Sir Sidetrack," he said. "If I may, a word of advice for the prompter. Most of the time you will not need me at all. I only come when something is standing guard where it should not. When that happens, you will know. Then simply ask me to run a small errand."

"What kind of errand?" asked Inkling.

"Would you be so kind as to step aside, that kind," said Sir Sidetrack, and sat down again, and sipped his tea.

Last of all, at the very back, polishing a small brass bell, sat a young hedgehog who did not look up at all.

"That is Kester," said the Captain. "Kester finishes things."

"Someone has to put the last plank down," said Kester the Finisher, still polishing. "Call me at the end. Not before. I'm no good at the middle."

Inkling wrote all their names in a column down the side of her page, and next to each one, in her smallest handwriting, what they did. Pinwell: pins. Crossfire: two at once. Gable and Garrett: straight lines. Sidetrack: errands. Kester: the end. Next to Captain Castle she wrote a question mark, because he had not said what he did, and she had a feeling it was important.

That evening, when the other children had gone home, the Captain lit the lamps in the hall and told Inkling the story of the game.

"It was the autumn of 1858," he said. "In Paris there was an opera house called the Italian Opera, and in it there were private boxes, little rooms with red curtains and gold chairs that hang over the stage like balconies. In one of those boxes sat a young American named Paul Morphy."

"Was he a good player?" asked Inkling.

"He was the best player in the world," said the Captain, "though he was only twenty-one, and though he would stop playing seriously a year or two later and never really start again. That is a different story." He smiled. "That night he had been invited to the opera by a duke. The Duke of Brunswick, a very rich man who loved chess and loved opera, and who had brought along his friend Count Isouard. The duke and the count wanted to play Morphy. So they set up a board in the box and played him together, the two of them against one. They whispered over every move."

"Two against one isn't fair," said Inkling.

"No," said the Captain. "And it did not help them in the least. Two heads are better than one at many things, but not at bringing your pieces out when you are both thinking about something else."

"What opera was it?" asked Inkling. She had her pencil ready.

The Captain was quiet for a moment. "Ah," he said. "Now there you have caught me. Nobody is quite sure. Some say it was Norma. The best guess, from people who have searched the old newspapers, is The Barber of Seville, on the fourth of November. But nobody wrote it down on the score sheet, so we cannot be certain. When we tell the story we will say The Barber of Seville, and we will also say that it is a guess."

Inkling liked that. She wrote: Barber of Seville (probably). Nobody wrote it down. Then she wrote underneath, Write things down.

"And they say," the Captain went on, "that Morphy sat facing the stage. That he wanted to watch the singing, and kept looking up from the board. Perhaps it is true. It is the kind of thing people say about clever young men. But the moves are true. Those we have, all of them, from the first pawn to the last rook. Thirty-three moves between them, seventeen for Morphy. Every one is written down."

He set the big pieces in their starting places, one by one. The white pieces gleamed. The black pieces stood in their rows like a crowd waiting for a bus.

"Here is what I want you to watch for," said Captain Castle. "Not who takes what. Anybody can count captures. I want you to count pieces in play. Every few moves, ask: how many of White's pieces are helping? How many of Black's? Count the pieces in play, not the pieces on the board."

"Why?" asked Inkling.

"Because that," said the Captain, "is what the whole game is about. You'll see."

Inkling walked home along the slow road in the dark, with the lake on her left and the stars coming out over it one at a time. At home her grandmother was still awake, sitting by the stove with her mending.

"Well?" said her grandmother. "Did the Captain give you a job?"

"I'm the prompter," said Inkling. "I have to say who comes next. In a famous game. From Paris." She took out the folding chessboard with the squeaky hinge and set it up on the kitchen table. "He says the whole game is about counting pieces in play. Not pieces on the board."

Her grandmother put down her mending and came to look. "Show me the first moves," she said.

Inkling showed her, as far as she knew them. Her grandmother watched with her chin in her hand.

"When I was a girl," said her grandmother, "my father used to say a game is like a party. You can have the finest cake in the world, but if half your guests are still standing in the hall with their coats on, it is not much of a party."

Inkling laughed. "The Captain says that too. Everyone comes to the party."

"Then he is a sensible rook," said her grandmother, and went back to her mending.

The first rehearsal was the next morning. The faculty came in one by one and took their places along the side of the hall. Inkling stood beside the big board with her notebook and a list of the moves, which she was not supposed to look at until she had guessed.

The first moves were easy. Captain Castle played them himself, walking the big pieces across the squares while the children watched.

White pushed the king's pawn two squares. 1. e4. Black did the same. 1... e5. White brought out a knight to defend nothing and attack the black pawn. 2. Nf3. Black protected the pawn with another pawn, a cautious little step. 2... d6.

"That's called Philidor's Defence," whispered a boy in the front row, who knew a great many names.

White pushed a second pawn into the middle. 3. d4.

And then Black's bishop, the one on the queen's side, came sliding out along its diagonal and stopped on g4, right in front of White's knight.

Inkling saw it at once. The white knight on f3 now stood between the black bishop and the white queen. If the knight moved, the bishop could take the queen. The knight was stuck. It was frozen to its square, holding up the queen behind it, just like the book on the library shelf.

"A pin!" said Inkling, very loudly. "That's a pin! That's a great pin! That's Sir Pinwell's move!"

Every head in the hall turned to the side of the room where Sir Pinwell was sitting.

Sir Pinwell was a bishop, tall and narrow, with his notebook on his knee and a pencil behind his mitre. He did not enjoy speaking very much. He looked at the board for a long time before he said anything at all.

"Hmm," said Sir Pinwell.

Inkling waited. Her face was already pink with pride.

"It is a pin," said Sir Pinwell at last. "You named it correctly. But I would wait one move before naming it. A pin is not just a piece in front of another piece. A pin is a promise. It says: I will hold you here. The question is whether Black can keep that promise."

"Can't he?" said Inkling.

"Look at what is attacking his bishop," said Sir Pinwell quietly.

Inkling looked. Nothing was attacking the bishop yet. But the white pawn on d4 was already pushing at the black pawn on e5. If White took that pawn, the queen's file would open, and the bishop on g4 would be sitting there in the middle of everything with no friends nearby.

"I don't know yet," said Inkling. Her face was still pink, but for a different reason now.

"Neither do I," said Sir Pinwell. "That is why one waits." He wrote something in his notebook. Inkling, standing close, saw what it was: She saw the line. Good. She named it too soon. Also good. That is how one learns when.

She did not know whether to feel pleased or embarrassed, so she felt both, and wrote down Wait one move in very small letters at the bottom of her page.

The next morning they played on from the same position.

White took the black pawn. 4. dxe5. Now Black had a choice. If Black took back with the pawn, the queens would come off down the open file, and Black's king would have to take back. Then Black could never castle. So Black did something else. The bishop on g4, the pinning bishop, took the knight it had been pinning. 4... Bxf3.

"He gave it away!" said the boy in the front row. "He gave the pin away!"

"Not away, exactly," said Captain Castle. "He traded. Bishop for knight. That is a fair trade on most days."

White took back with the queen. 5. Qxf3. And then, at last, Black took the pawn. 5... dxe5.

Inkling stared at the board. A minute ago the white queen had been stuck at home, hidden behind a frozen knight. Now the knight was gone, and the queen stood on f3, out in the open, looking straight down the diagonal at the black pawn on f7.

"Sir Pinwell," she said slowly. "The pin. It didn't last."

"No," said Sir Pinwell. "A pin you cannot keep is not a pin. It is just a bishop standing in the wrong place for a little while." He tapped the empty square where the black bishop had been. "And look what it cost. To keep his promise, Black had to spend his bishop. Now White's queen is free and Black's bishop is gone."

"So it was a bad pin?"

"It was a pin that Black could not afford to keep," said Sir Pinwell. "That is different. I am not saying it was wicked. I am saying it was early."

Inkling looked at the line she had written yesterday: A pin! A great pin! She drew a careful line through the word great, and wrote next to it, early.

Captain Castle stood up from his stool and walked along the front of the board.

"Now," said the Captain. "Count the pieces in play. Not the pieces on the board. The pieces that are actually doing something."

The children counted aloud.

White had a queen in the middle of the board, a pawn on e4, and a bishop and a knight that could come out next move. Black had a pawn on e5, a knight that had not moved, a bishop that had not moved, a queen that had not moved, and a king that was beginning to look a little lonely.

"White has one piece out," said a girl near the window. "Black has none."

"Black had one," said Inkling. "But he spent it."

"Exactly," said the Captain. "Everyone comes to the party, eventually. The question is whether they come in time."

On the third morning, the double doors at the back of the hall swung inward with a bang.

"GOOD MORNING, CHILDREN!"

The voice arrived before the man did. Captain Crossfire followed it in, ducking under the lintel because he was tall and the lintel was not. His long blue coat caught on the doorframe and came free with a flourish he definitely meant. His white hair was tied back at the neck.

"I hear," said Captain Crossfire, striding down the hall, "that we are re-staging the Opera Game. And I hear that I am in it. WATCH THIS!"

He had not even reached the board yet. The children sat up straighter. They could not help it.

White brought out a bishop. 6. Bc4. Black brought out a knight. 6... Nf6. The black knight now stood in front of Black's king, and Black was finally beginning to get some pieces out.

"Inkling," said Captain Castle. "Who comes next?"

Inkling looked at the board very hard. She remembered yesterday. She did not want to be loud and early again. So she counted instead. The white queen was on f3. The white bishop was on c4. The bishop looked down a long diagonal: c4, d5, e6, f7. Behind f7 was the black king's home square.

Then she looked at the queen. If the queen went to b3, it would look down the b-file at the black pawn on b7. And it would also stand behind the bishop on the c4 diagonal, both of them aiming at f7.

"Captain Crossfire," said Inkling. "Queen to b3. It hits two things."

"YES!" said Captain Crossfire. "EXACTLY! Two targets with ONE move!"

He picked up the big white queen and swept her across to b3.

7. Qb3.

"Go on, guess!" said Captain Crossfire, spinning round to face the children. "What is she looking at? Two things! Name them both!"

"The pawn on b7," said the girl near the window.

"And f7," said Inkling. "Behind the bishop. They're lined up."

"Never one threat when you can have two!" said Captain Crossfire, delighted. He clapped Inkling on the shoulder so hard her notebook nearly fell out of her pocket. "If Black guards one, the other falls. That is a double attack, my friends. One move, two problems. Black can only answer one of them."

Black answered by bringing out the queen. 7... Qe7. The black queen now guarded f7, and stood in front of her own king's bishop.

Sir Pinwell made a small noise. It might have been "Hmm."

"What?" said Inkling.

"Look where she is standing," said Sir Pinwell. "In front of her own bishop. The bishop on f8 still cannot get out. Black has guarded f7. But Black has also blocked a door."

Inkling wrote it down. Guarding one thing can block another.

At break, Captain Crossfire would not sit down. He set up a little board on the end of a table and gathered the younger children round it.

"Go on, guess!" said Captain Crossfire. "I put a knight here. What does it attack?"

"That rook," said one child.

"And?"

"That bishop," said another.

"YES! EXACTLY!" said Captain Crossfire. "Two targets with ONE move! Now, your turn. You are Black. You can save the rook, or you can save the bishop. Which do you save?"

The children argued about it for some time. In the end they saved the rook, because it was bigger, and Crossfire's knight gobbled up the bishop with a happy little hop.

"You see?" he said. "Never one threat when you can have two! One threat, your friend can answer. Two threats, your friend has to choose. And choosing is hard."

"Is it mean?" asked the very small boy, who asked a lot of questions.

Captain Crossfire looked surprised. Then he crouched down so that his blue coat spread out on the floor.

"It's not mean," he said, much more quietly than usual. "It's a question. A double attack asks your friend, which of these do you love more? Sometimes they find a clever answer. Sometimes they don't. Either way, you both learn something."

Inkling wrote that down too. She had not expected Captain Crossfire to say anything quietly.

White brought out the second knight. 8. Nc3. Black pushed a pawn to c6 to give the queen a little more room. 8... c6.

Then Captain Crossfire's eyes lit up like lanterns.

"Look at that!" he said, pointing. "The pawn on b7! Still undefended! The queen takes it, and then she takes the rook in the corner! WATCH THIS! Queen takes b7!"

He was already reaching for the big white queen.

Inkling looked at the board. It was true that the b7 pawn had nobody guarding it. It was true that the queen could take it. And it was true that Captain Crossfire was the one who had put the queen on b3 in the first place, so it seemed fair that he should be the one to finish the job. She opened her mouth to say yes.

Then she remembered wait one move. She remembered knowing a name is not the same as knowing when to say it. And she looked, very quickly, at what Black could do after the queen took b7.

"Sir Pinwell," said Inkling. "What happens if he takes it?"

Captain Crossfire's hand stopped in the air.

Sir Pinwell stood up. He walked to the board slowly, as if it might be resting.

"If White takes on b7," said Sir Pinwell, "then Black plays queen to b4. Now the queens face each other down the b-file, and Black is offering a trade. If White takes it, Black's bishop takes back." He moved the pieces as he spoke, gently, and then put them back. "The queens come off the board. And with the queens gone, White's attack is gone. Morphy would have a pawn more, and nothing else."

Captain Crossfire looked at the board for a long, long time. Inkling had never seen him so quiet.

"Ah," said Captain Crossfire at last. "I see. I see it. I'd have won a pawn and lost the party."

"You would have won a pawn," said Sir Pinwell. "That is not nothing. But Morphy was not playing for a pawn."

"Then what was he playing for?" asked the boy in the front row.

"For every piece," said Captain Castle from his stool. "Count them. White has a queen, two knights, a bishop. Black has a queen, one knight, and a lot of furniture that hasn't moved."

Inkling took a breath. Her job was to call the next one, so she called it.

"Sir Pinwell," she said. "A pin. The black knight on f6. If the bishop goes to g5, the knight can't move, because the queen on e7 is behind it."

Sir Pinwell looked at her. Then, for the first time that week, he smiled.

"Now," he said, "you have named it at the right time."

He played the bishop to g5. 9. Bg5. The black knight on f6 froze to its square, holding up the queen behind it.

Captain Crossfire laughed suddenly, a big laugh that filled the hall. "Well!" he said. "Two pins in one game! One for each side! But only one of them is going to last!"

"Why?" asked Inkling, because now it was her turn to make someone else explain.

"Because White can bring more pieces to hold it," said Captain Crossfire, "and Black can't bring more pieces to break it. Black hasn't got any more pieces out!"

Inkling wrote, in letters a little bigger than usual: A pin lasts if you can keep it.

Black pushed a pawn forward, trying to chase White's bishop off its diagonal. 9... b5.

"Who's next?" said Captain Castle.

Inkling frowned. This one was not in anyone's name. The pawn on b5 was attacking the white bishop on c4. White could move the bishop away. White could defend it. Or White could do something else.

"Morphy gives up the knight," said the Captain softly. "Watch."

He walked the white knight forward himself and put it on b5, taking the pawn. 10. Nxb5.

The hall went very quiet.

"But it's free!" said the boy in the front row. "The c6 pawn can take it!"

"It can," said the Captain. And Black's pawn did take it. 10... cxb5.

Inkling looked at what was left. Where there had been black pawns on b7 and c6, now there was only one pawn, on b5. And from b5 there was an open diagonal straight to the black king: b5, c6, d7, e8.

She understood, suddenly, why Morphy had given the knight away. It was not a gift. It was a key. The knight had been standing in front of a locked door, and Morphy had spent it to open the door.

"The bishop," said Inkling. "The bishop on c4 takes on b5, and it's check."

"And then?" said Sir Pinwell.

She thought about it. Black would have to block the check. The only piece that could get in the way was the knight on b8, which could jump to d7. And if the knight stood on d7, between the bishop and the king, then the knight would be frozen. It could not move without uncovering the king.

"Then it's your move again," said Inkling. "It's a pin. To the king, this time. That's the kind that can't ever move."

"Hmm," said Sir Pinwell. He sounded pleased. He took the bishop from c4 and set it on b5. 11. Bxb5+. Check.

Black's knight jumped out from b8 to d7 to block it. 11... Nbd7.

The black knight on d7 was frozen. The black knight on f6 was frozen. Two black knights, both stuck, and the black king behind them, still in the middle of the board with nowhere to hide.

"That," said Sir Pinwell quietly, "is a pin you can keep."

On the fourth morning, Captain Castle did not sit on his stool.

He stood beside the board with his hands behind his back, and his brass buttons caught the light from the high windows. The children could tell something was different. They stopped fidgeting without being asked.

"Inkling," said the Captain. "Who comes next?"

Inkling studied the position. White had a bishop pinning the knight on d7 to the black king. White had a bishop pinning the knight on f6 to the black queen. White had a queen on b3 and a knight on c3. White's king was still in the middle, at home on e1, with a rook in each corner.

Black was threatening nothing. Black's king was stuck in the middle too. Black's rooks had not moved. Black's bishop on f8 had not moved.

What did White need? Inkling thought about the knight on d7. It was pinned, but it was also guarded. If White wanted to win it, White would need to attack it more times than Black could defend it. And the d-file, running straight up from d1 to d7, was open now that the pawns had been traded.

A rook. White needed a rook on the d-file.

And there was one move in chess that brought a rook to the d-file and tucked the king away at the same time.

"You," said Inkling. "Captain Castle. Castling. Queen's side."

The Captain looked at her for a long moment. Then he bowed, a small, square, rook-shaped bow.

"Tuck the king in and bring the rook out," said Captain Castle. "That's the whole move. One turn, two jobs."

He walked to the white king on e1 and moved it two squares toward the queen's side, to c1. Then he picked up the rook from the a1 corner and swung it over the king to d1. The king was now tucked behind three pawns, safe as a cat in a basket. The rook stood on d1, at the bottom of the open file, looking straight up at the frozen knight.

12. O-O-O.

Some of the younger children clapped. They did not entirely know why, but it looked like the kind of move you were supposed to clap for.

"Why did you choose that one?" asked the girl near the window. "To play yourself, I mean."

"Because it is the move I like best," said the Captain simply. He went back to his stool and sat down. "People think castling is a hiding move. A coward's move. It is not. Look." He pointed. "Before this move, White's king was in danger and the rook was asleep in the corner. After this move, the king is safe and the rook is awake. It is the only move in the whole game where one piece gets safer and another gets busier at the same time."

Inkling wrote: Castling = king safe + rook busy. Then she thought, and added: Black never castled. Black's king is still in the middle. Black's rooks are still asleep.

She counted the pieces in play again.

White had the queen, both bishops, a knight, a rook and a safe king. Black had a queen, two frozen knights, and a king who was beginning to look as if he wished he had gone to the opera and watched the singing instead.

Black tried to wake up a rook. 12... Rd8. The black rook from a8 slid over to d8, to stand behind the frozen knight and help guard it.

"There," said the Captain. "Now Black has a rook in play. One. It is a little late."

Gable and Garrett were twins, and they were towers. They walked in straight lines and they always walked together, one a step in front of the other. When one of them started a sentence, the other finished it.

They came in on the fifth morning, side by side, so tall that their tops nearly brushed the beams.

"We hear there's a file—" said Gable.

"—an open one," said Garrett.

Inkling had been waiting for them. She had stayed up late the night before with her grandmother's chessboard, setting up the position over and over and trying to see what came next. She had found it in the end. She had nearly called it at breakfast.

"The knight on d7," she said. "It's pinned. White has the rook on d1 and the bishop on b5 attacking it. Black has the knight on f6, the rook on d8 and the queen on e7 guarding it. Three attackers would beat three defenders, but White only has two. So White can't just take it and win it."

"Then what?" said Captain Castle.

"Then White takes it anyway," said Inkling. "With the rook. And when Black takes back with the rook, that rook is pinned instead. And the other white rook comes in behind."

"One of us goes first—" said Gable.

"—and the other comes behind," said Garrett.

Gable took the knight on d7 with the white rook. 13. Rxd7. Black's rook from d8 took back. 13... Rxd7.

And now the black rook stood on d7, exactly where the knight had been. The white bishop on b5 was still looking down the diagonal through d7 to the black king on e8. The rook was frozen now, just as the knight had been.

"Straight lines only," said Garrett, stepping onto the board. He took the other white rook from the h1 corner and slid it all the way across to d1. 14. Rd1.

Now there were two white pieces aiming at the frozen rook on d7: the rook on d1 below it and the bishop on b5 beside it. And the black rook could not run away, because if it moved, the bishop would give check to the king.

"Open file, open road," said Gable.

"Together we're twice as heavy," said Garrett.

Afterwards the twins showed the younger children what they meant, on a small board at the side of the hall. They set up an empty file, just one rook at the bottom and a black piece at the top.

"One of us alone can push," said Gable. "But if the black piece has a friend guarding it—"

"—then one push isn't enough," said Garrett. He put a second rook behind the first. "Now there are two of us on the same line. When the front one takes and gets taken back—"

"—the one behind takes again," said Gable. "Straight lines only. One goes, the next one comes. That's called doubling."

"Is it like holding hands?" asked a very small boy.

The twins looked at each other. It was hard to tell, with towers, but Inkling was fairly sure they were pleased.

"Exactly like holding hands," said Garrett. "In a straight line."

Inkling watched them and thought about the bridge her friend Lan had told her about, on the island of Gullwick, where everybody laid one plank. A file was like a bridge, she decided. One piece could not hold it alone. But one behind another, they could.

"Why didn't White take with the bishop first?" asked the boy in the front row. "Wouldn't that be safer?"

"Because then the bishop's line would be gone," said Inkling, before anyone else could answer. Then she put her hand over her mouth. She had done it again. Named it too soon.

But Sir Pinwell, at the side of the hall, nodded. "Go on," he said.

Inkling took her hand away. "If the bishop takes on d7, the pin is used up," she said. "The bishop can only take once. But if the rook takes, then Black's rook comes into the pin, and the bishop is still there holding it. The pin keeps working. You let the pin keep working while the others come."

"Pinwell holds," said Captain Castle, "while the attack arrives."

Sir Pinwell said nothing at all. But he wrote something in his notebook, and he showed it to Inkling afterwards. It said: She named it at the right time. That is twice.

Black brought the queen across to try to help. 14... Qe6. The black queen now looked across the board at the white queen on b3, hoping to trade her off. It was too late.

The sixth morning was the last rehearsal before Lantern Night.

White took the frozen rook on d7 with the bishop, giving check. 15. Bxd7+. Sir Pinwell played it himself, very quietly, and the bishop came to rest beside the black king like a librarian returning a book to its proper shelf. The black knight on f6 took it back. 15... Nxd7. It was the only piece that could.

Now the board was nearly empty around the black king. The black king stood on e8. The black knight stood on d7. The black queen stood on e6. The black bishop on f8 and the black rook on h8 stood exactly where they had stood at the start of the game.

White had a queen on b3, a bishop on g5 and a rook on d1. That was all. White had given away a knight, a bishop and a rook to get here.

"Material," said Captain Castle, "is all even, or worse for White. Count it if you like. But count the pieces in play first."

Inkling counted. White had three pieces in play, and every one of them was aimed at the black king. Black had two pieces near the king, and both of them were busy guarding something.

"Now," said the Captain. "Who comes next? This is the moment Morphy found. If you can find it, you will understand the whole game."

The hall was very quiet.

Stop here, reader, before you turn the page. Look at the board in your head, or set it up if you have one. Who would you send? Captain Crossfire, with a double attack? Kester the Finisher, to end it? Sir Pinwell, with another pin? Or someone else?

Inkling looked at the rook on d1. If the rook could get to d8, it would be checkmate. The king would have no squares, nothing could take the rook, and nothing could block it. But the rook could not get to d8, because the black knight on d7 was standing in the way.

So the knight had to move. And the knight would only move if it had to.

She looked at the white queen on b3. If the queen went to b8, it would give check to the king. The king could not move out of check, because e7 and d8 were covered. The only way to deal with the check was to take the queen. And the only piece that could take the queen on b8 was the knight on d7.

The knight would have to leave d7. And then the d-file would be open, all the way from d1 to d8.

"Kester can't finish it yet," said Inkling slowly. At the back of the hall, Kester had put down his bell.

"I could finish it," said Kester the Finisher, standing up. "If the rook gets to d8, there are no squares left."

"But the rook can't get to d8," said Inkling. "Not yet. The knight is in the way."

Kester looked at the board for a long moment, calm as a pond. "Then it isn't the end," he said, and sat down again. "Call me when it is the end. Almost is not the same as done."

Inkling turned back to the board. "The knight is in the way. Somebody has to chase the knight away first. Somebody has to ask it, very politely, to step aside."

She turned to the side of the hall, where a lean stoat in a travelling cloak was sitting with his legs crossed, looking as if none of this were any of his business.

"Sir Sidetrack," said Inkling.

Sir Sidetrack uncrossed his legs.

"If I may," said Sir Sidetrack, rising with a little bow. He walked to the board without hurrying. "Would you be so kind as to step aside?"

He picked up the white queen, the most powerful piece on the board, and set her down on b8, right in front of the black knight.

16. Qb8+.

A gasp went round the hall.

"He's giving away the queen!" said the boy in the front row.

"A small errand, nothing more," said Sir Sidetrack mildly. "The guard cannot be in two places. If it takes my queen, it leaves its post. If it stays at its post, its king is in check and has nowhere to go."

The black knight had no choice. It jumped from d7 to b8 and took the queen. 16... Nxb8.

And the d-file was open.

"Kester," said Inkling.

Kester the Finisher was a young hedgehog who finished things. He had been sitting at the very back of the hall all week, polishing a small brass bell, waiting. In the market town where he had grown up, everyone was good at starting things and nobody was good at finishing them. Kester was the one who put the last plank down.

He stood up, put the bell in his pocket, and walked to the board.

"Then I'll finish it," said Kester the Finisher.

He took the white rook from d1 and slid it all the way up the empty file to d8.

17. Rd8#.

"Escape, block or capture," said Kester. "None of them."

The children leaned forward to look. The black king on e8 was in check from the rook on d8. It could not move to e7, because the bishop on g5 guarded that square. It could not move to d7, because the rook guarded it. It could not move to f7, because its own pawn was there. Nothing could take the rook, because the white bishop on g5 was quietly watching d8 through e7. Nothing could block it, because the rook was right next to the king.

"No squares left," said Kester. "Done."

Checkmate.

Nobody said anything for a moment. Then the whole hall began to clap, and some of the younger children stood on the benches, and Captain Crossfire shouted "YES! EXACTLY!" so loudly that a pigeon flew off the roof.

When it was quiet again, Captain Castle stood up.

"Now," he said. "One last count. Look at Black's pieces. Which of them never moved, from the first move to the last?"

Inkling looked. The black bishop on f8 was still on f8. The black rook on h8 was still on h8. They had sat in their corner the whole game, all seventeen moves, like guests who had arrived at a party and never taken off their coats.

"The bishop and the rook on the king's side," said Inkling. "They never came."

"And how many pieces did Morphy use to give checkmate?" asked the Captain.

"Two," said Inkling. "His last rook and his last bishop."

"He gave away a knight, a bishop, a rook and his queen," said Captain Castle. "He had only two pieces left. But every single one of his pieces had come to the party. And two of Black's had not." He smiled. "Morphy did not count material. He counted pieces in play. That is the whole lesson. Everyone comes to the party."

Inkling wrote it down at the bottom of her page, in big letters: EVERYONE COMES TO THE PARTY. Then, under it, smaller: But not everyone comes at once. You have to know when.

On Lantern Night the whole village came.

They came with paper lanterns on sticks, and they filled the academy hall until there was nowhere left to stand, and they sat on the window sills and on each other's laps. The baker came. The librarian's assistant came. Inkling's grandmother came, with her own folding chessboard under her arm, the one with the squeaky hinge.

Inkling stood beside the big board with her notebook. She did not need to look at it. She knew every move now. But she held it anyway, because it was nice to hold.

The first moves went by quickly. When Black's bishop came out to pin the knight, Inkling did not shout. She waited one move. When the bishop took the knight, she said, clearly, so the back rows could hear: "A pin you cannot keep is not a pin." And Sir Pinwell, at the side of the hall, gave her the smallest nod in the world.

When it was Captain Crossfire's turn, she called him, and he swept the queen to b3 so fast his coat flew out behind him. When it was nearly his turn again, and he looked at the pawn on b7 with shining eyes, she called Sir Pinwell instead. Crossfire laughed and threw up his hands. "Right again!" he said. "I'd have won a pawn and lost the party!"

When it was Captain Castle's turn, the old rook castled with such care that the whole hall held its breath. When it was the twins' turn, Gable and Garrett walked onto the board one behind the other, and the children in the front row said "—and the other comes behind!" with them.

And when it was time for the queen to be given away, Inkling stopped.

She turned round to the audience.

"Who comes next?" she asked them.

There was a pause. Then a small voice at the back, a girl of about six on her father's shoulders, called out, "The one who asks politely!"

Sir Sidetrack bowed to the girl, very low, and played the queen to b8. Kester finished it. The hall went up like a firework.

Later, when the crowd had spilled out onto the green with their lanterns, Inkling found the faculty sitting together on the academy steps, drinking cocoa.

"You gave the queen away in front of the whole village," said Captain Crossfire to Sir Sidetrack, shaking his head. "The QUEEN! I've never had the nerve. I always want to keep her and fire her at two things at once!"

"After you," said Sir Sidetrack politely, offering him the biscuit tin. "A queen is only a piece, my friend. Pieces are for using. The guard cannot be in two places, and someone has to remind it."

"And then I finish it," said Kester the Finisher, who had cocoa on his nose. "That's the part I like. No squares left. Done."

"One of us went first—" said Gable.

"—and the other came behind," said Garrett. "Like always."

Sir Pinwell said nothing at all. He was writing in his notebook. Inkling leaned over to look. It said: The prompter waited one move, every time. Lantern Night, a success.

"Hmm," said Sir Pinwell, and closed the notebook before she could read any more.

Afterwards, while the lanterns were being lit for the walk home, Captain Castle gave Inkling a sheet of paper. On it, in his square, careful handwriting, were all thirty-three moves of the Opera Game, numbered, with the date and the place at the top and a question mark after the name of the opera.

"The second of four," said the Captain. "Next term we will do the Immortal Game. Keep this somewhere safe. When you have four, you will have the start of a scorebook of your own."

The spark was waiting on the brass rook knocker when she came out. It looked a little brighter than before.

The spark dimmed to a warm dot and settled back on the anvil. The Green was just the Green again.

Back on the Green

The next Saturday it was Grandmother's birthday, and Inkling was in charge of the party.

The year before, her cousins had all tried to help at once. Three of them had iced the cake and nobody had laid the table. This year Inkling did it differently. She did not shout names. She watched first. She noticed who was good at what. Then she gave each cousin one job, at the right moment: the little one put out the spoons, the tall one hung the lantern, the quiet one carried the cake. Nobody stood in the corner with their coat on.

When the cake came in, Grandmother looked round the room at everyone helping and laughed.

"Everyone came to the party," she said.

Tell the story back to someone in your own words. Then set up a board, or draw one, and play the last five moves of the Opera Game with a grown-up. You take Morphy's side.