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

Inkling saw it first, because Inkling saw most things first. Beto saw it second, because he was busy taking the back off an old radio and only looked up when Inkling grabbed his sleeve.

The spark did not float the way sparks are supposed to. It hopped. It hopped across the grass of the Green, past the bench and the big oak, all the way to the far edge where the lane begins. There, under the trees, stood a little wooden cart.

The cart had two tall wheels and a canvas roof. On the back sat a small black forge, round as a cooking pot, with a leather bellows beside it. A brass bell hung from a hook. Boxes of scrap were stacked everywhere: springs, keys, bent nails, a teapot spout, a single bicycle pedal.

The spark dropped into the forge. The cold coals woke up red.

A face looked out from under the canvas. It was a young raccoon, with a black mask round her bright eyes, a striped jumper, and soot on both her paws.

"Oh, good," said the raccoon. "You came. I'm Fiddle. That spark only ever lands in my coals when a town has broken something."

"What did they break?" said Inkling.

"I don't know yet," said Fiddle happily. "Try it and see."

She held out two leather tool belts. They had little loops and pockets all along them, and every loop was empty.

"What are these for?" said Beto. He was already turning his over to see how the buckle worked.

"For the tools you make," said Fiddle. "You don't buy them and you don't find them. You make them, after you mend something. Then you tell the story back, and then it's yours."

Inkling buckled hers on at once. Beto took his buckle apart, looked at it, put it back together, and then buckled it on.

They climbed up beside Fiddle. She tugged a cord, and the brass bell swung.

The cart's bell rang once, and the wheels began to turn.

They smelled the town before they saw it.

It was the smell of toast left too long. Then the smell of toast left much too long. By the time the cart rolled over a little stone bridge and into a square of crooked houses, the air was grey and bitter and everybody was coughing.

"Tickwell," said Fiddle, reading a painted sign. "Mind the step."

A baker stood in the doorway of his shop, holding a tray of loaves as black as coal. He looked as if he might cry.

"The clock said fifty-two minutes," said the baker. "I watched it. I trusted it. My loaves were in for the hour."

In the middle of the square stood a tall clock. It was taller than the baker's door, with a white face, two black hands, and a glass door below the face. Behind the glass, a long pendulum swung from side to side, tick, tock, tick, tock.

Under the clock sat a tortoise. Her shell was not a plain shell. It had numbers round the edge, and two small hands, and a tiny seconds hand that went round and round.

"Good morning," said the tortoise. "I am Tock. I keep time in Tickwell. Or I try to."

"Is the clock broken?" said Inkling.

"It skips," said Tock. "Yesterday the school bell rang so late that the children ate lunch at teatime. The day before, nobody noticed a thing." She looked up at the tall clock sadly. "A clock is only as good as its beat."

Beto stared at the pendulum. Tick, tock. Tick, tock. It looked steady. It sounded steady. He frowned.

"Why would it skip?" said Beto. "It looks fine."

"Many things look fine," said Tock. "That is why we check them."

All round the square, Tickwell was having a muddled day. A girl ran past with her school bag, sure she was late, and then stopped, because the school door was still locked. A man was still setting out the market stalls as if it were early morning, though the sun was high. An old goat sat on a bench with a pocket watch in his hoof, shaking it and holding it to his ear.

"Everybody sets their watch by the big clock," said Tock. "So when the big clock is wrong, everybody is wrong together. That is the trouble with one clock for a whole town."

"Then the town needs a clock it can trust," said Inkling.

"Yes," said Tock. "And a way to know when it can't."

Inkling walked all the way round the clock. Then she walked round it again. She looked at the white face and the two black hands and the little door below the face, where a key went in.

Inkling liked to name things. When she named a thing, it felt as if she had caught it.

"It's the hands. I can name it," said Inkling. "The hands are wrong, so we push them to the right time!"

She stood on her toes and reached for the little door.

"Wait. Check it against a beat you trust," said Tock. She did not shout. She did not need to. "If you push the hands, the clock will say the right time today. Tomorrow it will drift again. The hands only show the beat. If the beat is wrong, the hands will be wrong."

Inkling's hand stopped in the air. Her cheeks went hot.

She had done it again. She had named the thing before she knew what the thing was. Her mother called it jumping to the end of the book.

"Sorry," said Inkling quietly.

"There's nothing to be sorry for," said Fiddle. "You tried an idea. Now you know one thing it isn't." She sat down on the cart step and folded her paws. "So. What is it?"

Inkling looked at her. Fiddle looked back, cheerful, and said nothing at all.

"Aren't you going to tell us?" said Beto.

"I won't tell you. It will," said Fiddle, and nodded at the clock.

"If we want to know whether a clock is right," said Tock, "we need a beat we already trust. Mine is my shell. I have checked it against the sun every day for a hundred years."

"A hundred years?" said Inkling.

"Tortoises are patient," said Tock. "Count with me, slow and steady. Sixty seconds make one minute. I will watch my seconds hand go all the way round, once. While I watch, one of you counts the swings of the pendulum. Each swing one way counts as one."

"I'll count," said Beto. He liked counting. Counting was a kind of taking apart.

Tock lifted one foot. "Now."

Tick, tock. Beto counted under his breath. Inkling counted too, silently, moving her lips. The pendulum swung, and swung, and swung. Tock's seconds hand crept round her shell. A gull landed on the clock and flew off again. The baker came out to watch.

"Stop," said Tock.

"Fifty-two," said Beto. "Why only fifty-two?"

"In one true minute, a good clock's pendulum swings sixty times," said Tock. "This one swings fifty-two. Sixty take away fifty-two is eight. So every minute, this clock thinks only fifty-two seconds have passed. It loses eight seconds every minute."

Inkling did the next part on her fingers, then gave up and used the dusty ground. Eight seconds every minute. There are sixty minutes in an hour. Eight times sixty is four hundred and eighty seconds. And sixty seconds is a minute, so four hundred and eighty seconds is eight minutes.

"It loses eight whole minutes every hour!" said Inkling.

"That's why the bread burnt," said Beto. "The clock was slow, so the baker waited too long."

The baker nodded slowly and looked at his black loaves. "Eight minutes, every hour," he said. "No wonder."

Tock looked pleased. "Now you know what is wrong," she said. "You don't know why yet."

Beto turned to Fiddle. "What makes a clock slow?"

"Try it and see," said Fiddle.

"But you know," said Beto. "You're a tinker. You fix things."

"I fix things by trying them," said Fiddle. "So will you. What does the metal tell you?"

Beto looked at the clock. He looked at the glass door below the face. It had a small brass catch.

"Can I open it?" he said to Tock.

"Gently," said Tock.

Beto opened the glass door. Inside, the pendulum was bigger than it looked from outside. It was a long wooden rod, thin and straight, with a heavy round brass weight near the bottom. The weight was as big as a saucer.

"Poke it gently, then look again," said Fiddle.

Beto put out one finger and touched the brass weight. Nothing happened. He pushed it up a little. Something did happen. The weight moved. It slid up the rod, just a tiny bit, and then slid back down when he let go.

"It moves!" said Beto. "The weight moves on the rod!"

"How does it work?" said Inkling. "Is it supposed to?"

Beto crouched down and looked underneath. Below the weight was a small brass nut, screwed onto the rod. It held the weight up, like a shelf.

"I think the nut holds it," said Beto. "But it's loose. Maybe it has turned, bit by bit. Maybe the weight has slipped down."

Fiddle clapped her sooty paws. "Push it, pull it, twist it, see," she said.

"But does it matter where the weight is?" said Inkling. "A weight is a weight."

Nobody answered her. Beto looked at Fiddle. Fiddle only smiled.

Something small and green climbed up the side of the clock case.

It was an inchworm. She looped up the wood, stretched out flat, looped up again, and stopped on the edge of the glass door.

"Hello," said the inchworm. "I'm Inchy. I measure things. I heard something has slipped."

"The weight," said Beto. "We think it has slid down the rod."

"Then let's find out how far," said Inchy. "End to end, no gaps. Start at the very end."

She crawled to the very top of the rod, where it hung from a little hook. She stretched her body out straight along the wood. Then she brought her back end up to her front end, so that she had moved exactly one of her own lengths. She did it again, and again.

"One Inchy, two Inchy, three," said Inchy. "Same size step, every time."

Inkling and Beto counted with her. Four Inchys. Five. Six. Seven. Eight. Inchy reached the brass weight and stopped.

"Eight," said Inchy. "From the hook to the weight is eight of me."

"Is that a lot?" said Beto.

"It's not a lot or a little," said Inchy. "It's eight. That's how many of me it is."

"Why don't you just guess?" said Beto. "It looks about as long as my arm."

"Your arm is not my arm," said Inchy kindly. "And your arm tomorrow is a bit longer than your arm today, because you are growing. If I use the same size step every time, and I lay my steps end to end with no gaps and no overlaps, then eight today is eight tomorrow. Anybody with an Inchy can check it."

"There's only one of you," said Inkling.

Inchy laughed, a small wriggly laugh. "Then anybody with a string cut to my length can check it. That's all a ruler is. The same step, over and over."

Then Inkling noticed something. She was good at noticing. On the inside of the wooden case, beside the rod, somebody long ago had scratched little marks into the wood, like the lines on a ruler. Most were faint. One was deeper than the others, and beside it was a tiny scratched number. Beside the number, smaller still, somebody had scratched a tiny hammer. Inkling looked at it for a long moment. It was not a name. It was only a hammer, as if whoever had mended this clock had wanted to say somebody was here without saying who.

"There's a mark here," said Inkling. "It says six."

Inchy crawled over to look. She measured from the hook down to the deep mark, end to end, no gaps. "Six," she said. "Six of me."

"So somebody once put the weight at six," said Beto slowly. "And now it's at eight."

"Eight take away six is two," said Inchy. "The weight has slid two lengths down."

Beto looked at Fiddle. "So the weight should be at six?"

"What does the metal tell you?" said Fiddle.

"It tells me there's a mark at six," said Beto. "It doesn't tell me why."

"Then let's find out why," said a voice.

A beaver had come up behind them with an armful of small logs. He set them down in a neat pile on the stones.

"I'm Stax," said the beaver. "Let's stack it up and see. You try the weight in three places. Tock times one minute for each. I put down one log for every swing you count. Then we look."

"One log for every swing?" said Inkling. "That's a lot of logs."

"Look at the bars, not the guesses," said Stax. "Line them up side by side."

So they tried it. First they left the weight where it was, at eight Inchys. Tock timed one true minute on her shell, and Beto counted. About fifty-two. Stax stacked fifty-two little logs into one tall bar. It took a while.

Next, Beto pushed the weight up one length and held it there while Inkling tied it with a bit of string from Fiddle's cart. Now it was at seven Inchys. Tock timed another minute. Beto counted again. About fifty-six. Stax stacked a second bar beside the first. It was a little taller.

Inkling looked at the two bars. The second was taller than the first, but only by a few logs.

"I bet the next one is taller again," said Inkling. "I can name the pattern already."

"Maybe," said Stax. "Maybe not. Let's stack it up and see. A guess is fine. A guess you check is better."

Inkling laughed. She was learning. She kept her guess in her head, where it could wait, and helped Beto with the string.

Then Beto pushed the weight up one more length, to the old mark at six. Inkling tied it again. Tock timed a minute. Beto counted carefully, out loud.

"Fifty-eight. Fifty-nine. Sixty," said Beto, just as Tock said, "Stop."

Stax stacked a third bar. It was the tallest of the three.

They stood back and looked. Three bars in a row: short, taller, tallest.

"The tall bar wins the argument," said Stax. "Look. When the weight was low, the swing was slow. When the weight was high, the swing was fast."

"I noticed something," said Inkling. "The shorter the pendulum, the more swings."

"A longer swing takes longer," said Beto. "So when the weight slid down, the pendulum got longer, and it swung slower, and the clock lost time."

"So the weight does matter," said Inkling. "It matters where it is."

Fiddle was grinning so hard her mask crinkled. She still said nothing.

The sun went low. The square went orange, then grey.

Beto wanted to see exactly how the nut worked before he tightened it. That is the kind of boy Beto was. So he lifted the pendulum off its little hook and laid it on the cart's step. Then he unscrewed the nut. Then he took off the brass weight. Then he found a tiny washer and a tiny spring and took those off too.

By the time it was dusk, the pendulum was in pieces all over the step. The clock in the square had stopped. Its hands pointed at nothing in particular.

And the little brass nut would not go back on. It was rusty. It had always been a bit rusty, Beto realised. That was probably why it had slipped. Now it was stuck halfway up the rod and would not turn either way.

Beto sat down on the stones. He was tired, and his fingers were sore, and the clock was more broken than when they had found it.

"I could take it apart," said Beto. "But how do I put it back?"

Inkling sat down next to him. She didn't say anything clever. She just sat.

After a while she said, "I wanted to push the hands. That was my mistake."

"This is mine," said Beto. He waved at the pieces. "I always take things apart to see how they work. Then I forget how they go back. My dad says I take the people apart too, by asking why, why, why, and then I forget to put them back together."

"What does that mean?" said Inkling.

"It means I forget to say thank you," said Beto. He looked at Tock. "Thank you for counting with us."

Tock blinked her slow tortoise blink. "You're welcome," she said. "Mistakes are only pieces. Pieces can go back."

Tock came over, very slowly, the way tortoises do. She didn't hurry him. She didn't say he had done it wrong.

"Tick, and tick, and tick," said Tock softly. "One piece at a time."

Beto looked at the pieces. Then he did something he had never done before. He laid them out in a row on the step, in the order they had come off. The spring at the end. The washer next to it. Then the weight. Then the nut.

"I'll put them back the other way round," he said. "The last one off goes on first."

Fiddle handed him a little can from the cart without a word. It was oil. Beto put one drop on the rusty nut and waited. He tried to turn it. Nothing. He waited a bit longer and tried again. It moved, just a hair. Then a bit more. Then it spun freely.

He put the pieces back on in the right order. He slid the brass weight up to the old scratch at six Inchys. Inchy checked it, end to end, no gaps.

"Six," said Inchy. "Exactly six of me."

Beto tightened the nut firmly underneath the weight, so it could not slip again. Then he hung the pendulum back on its hook and gave it a gentle push.

Tick, tock. Tick, tock.

"Count with me, slow and steady," said Tock. "Now."

Beto counted. Inkling counted. The baker counted. Inchy, Stax and half of Tickwell counted with them, there in the dark square.

"Sixty," said everyone at once.

Sixty swings in one true minute.

"Now," said Tock, "and only now, you may set the hands."

Inkling looked at Tock's shell to see the real time. Then she opened the little door on the clock face and pushed the hands, just once, to the right time.

"Fix the beat," said Inkling. "Then set the hands once."

"That's how many of me it took," said Inchy proudly, which didn't quite make sense, but everybody understood.

That night, the forge on the back of the cart glowed bright orange. Fiddle worked the bellows, and the coals roared.

"Every mend makes a tool," said Fiddle. "What should this one be?"

Inkling thought about it. "Something that keeps a steady beat," she said. "Something I can carry."

So Fiddle let them melt a little scrap of brass in a small clay cup. They poured it into a mould the size of a marble, and when it cooled, Beto drilled a hole through it and Inkling tied it to a long piece of string.

It was a tiny pendulum. A tick-weight.

Inkling hung it from one of the empty loops on her belt. It swung against her leg, tick, tock.

"Will it always swing sixty times?" said Inkling.

"Try it and see," said Fiddle.

Stax gave Beto one small log from the tallest bar. "To remember the pattern," he said. "Line them up side by side, and the answer stands up by itself."

Inchy gave Inkling nothing, because she had nothing to give, but she stretched out along the edge of the cart and said, "Eight of me, that cart is. I checked."

The baker gave them a warm loaf, golden all over, not burnt at all. Tock nodded to them from under the clock, and the clock struck nine exactly on time.

"Push it, pull it, twist it, see," said Fiddle. She tugged the cord.

The cart's bell rang twice, and the road ran home.

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 morning, Inkling stood in her kitchen and swung her tick-weight beside the clock on the wall. She counted the swings while the seconds hand went round. Forty swings. Too slow.

She remembered Stax's bars. A shorter swing is faster. So she wound the string round her finger to make it shorter and tried again. Seventy. Too fast. She let out a little string. Sixty-three. A little more. Sixty.

"I noticed something," said Inkling to nobody in particular. "Shorter is faster. I didn't name it first. I checked."

Her mother looked up from her coffee. "Checked what?"

Inkling held up the tick-weight. "Can I tell you a story?" she said.

Tell the story back to someone. Why didn't they just push the hands?