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

There were five of them that Monday. Tí was four and held his sister's hand. Lan was seven and wanted to be first. Inkling was eight and noticed things. Beto was nine and took things apart. Danya was twelve and asked how anyone knew anything.

The spark rolled across the Green to the door of Brightfield School. It stopped at the club room and settled on the step.

The club room smelled of crayons and toast. Long tables. A case board on the wall, bare. And by the door, an iron hook.

The hook was empty.

"Where's the bell?" asked Lan. "It rings at half past five. That's how we know to go home!"

Nobody knew. The bell had hung there for longer than any of them had been alive. Now there was only a pale square on the wall where it used to be.

"How do we know it was here today?" asked Danya.

"Because it rang to start club, at half past three," said Inkling. "I noticed it. It was loud."

Lan went first. She always did. She climbed onto a chair and reached for the empty hook.

"Wait! Draw it before you touch it," said Sketch.

A grey heron stood in the corner with a sketchbook under one wing. Lan had not seen her. Lan pulled her hand back. She was a bit cross.

"Why? It's just a hook," said Lan.

"A scene only tells its story once," said Sketch. "Hands in pockets, eyes open. If you rattle the hook, you might rub out the very thing we need."

Lan put her hands in her pockets. She did not like waiting. But she climbed down.

Sketch took the pencil from behind her ear. She drew slowly.

The hook. The pale square on the wall. And on the floor, three little scuffs in the dust, in a line.

"Mark where everything sits," said Sketch. "One scuff, two scuffs, three. And look where the line goes."

The line went under the long bench by the window.

"I see it," said Inkling. "I think it's pointing somewhere. Wait, I can name it. It's a trail."

"Look first, touch later," said Sketch. "Now we look."

Tí let go of Lan's hand. He put one finger on the drawing and followed the three scuffs. Then he followed them on the real floor, all the way under the bench.

"Look, a tiny one," said Tí. He came out with dust on his knees.

In his fist was a strip of paper. On it, in neat capital letters, were three words that were not words at all: DVN WKH FRRN.

"Mine. I'm holding it," said Tí. But he let Danya read it.

A fox in a striped scarf leaned over the table. A paper wheel was pinned to her scarf, two rings of letters, one inside the other.

"It's a shift code," said Kaesa. "Slide every letter the same number of steps. Try three."

She gave the wheel to Inkling. Inkling turned the inside ring back three steps.

"D slides back to A," said Inkling. "V goes to S. N goes to K. That makes ASK."

"Same shift, every letter," said Kaesa. "Keep going."

W went to T. K went to H. H went to E. THE. F went to C, and both Rs went to O, and the last N went to K. COOK.

"Ask the cook," read Lan. "Ask the cook what?"

"Count the steps, then slide," said Kaesa. "You did. Every letter moves together, so the message came out whole."

Danya stood at the bare case board. He took two pens, one black and one grey pencil.

"How do we know what we know?" asked Danya. "We split it."

He wrote WHAT WE SAW on one side and WHAT WE THINK on the other.

Under SAW, in ink: the empty hook, three scuffs, a strip, ASK THE COOK. He pinned up Sketch's drawing. It was the first card on the board.

Under THINK, in pencil: someone wants us to talk to the cook.

"Why pencil?" asked Tí.

"Because nobody has checked it yet," said Danya. "Who checked that? Nobody. So it stays grey."

The clock on the wall said twenty past five. With no bell, Lan watched the clock herself, and they packed up on time.

Back on the Green

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

At home, Tí's grandmother hid his slippers. Tí did not run around the room. He stood at the door and looked first. One slipper by the chair. A sock trail to the cupboard.

"Look, a tiny one," said Tí, and found them both.