Dad didn’t say much as they loaded the van that evening. They drove away from the big house. They parked the van in the clearing; the clock above the steering wheel said it was almost six. Dad undid his seat belt. Ethan got out. He wanted to run down the canal to Moon’s End, to write down everything Dad had said and show it to Polly. But there wasn’t time.

Ethan left half his shepherd’s pie at dinner.

“Not hungry?” Mum’s forehead crinkled up. She looked at him with narrow eyes. She reached across the fold-out table and took his plate.

“You should be after all that work,” said Dad.

“You look tired, Ethan,” said Mum. “I think you need an early night.”

Ethan didn’t shake his head. He wanted to go to his cabin. His whole body was heavy from carrying Dad’s tools and the bag of peat. He didn’t feel like sitting on the sofa with Mum and Dad.

Ethan pushed back his chair. He padded out of the lounge, through the engine room and into his cabin. He turned the latch at the top of his bed cupboard and the mattress and quilt unfolded. He tugged the quilt over his shoulders. The cabin was freezing cold, too cold to sleep. Even the little corner stove wasn’t warming it. Frosty air crept in through the little hole in the ceiling and wriggled into his bed. It nibbled the bit of bare skin between the top of his pyjamas and the bottom of his T-shirt. His feet were as cold as the water in the canal.

Ethan grabbed both sides of the quilt and pulled it tightly under him. Now he had a cocoon, like a caterpillar, to keep out the cold. He went over Dad’s words at the big house, again and again.

Sometimes it’s best not to remember, Ethan.

Sometimes it’s best to leave the past behind.

He went over the words so many times that they got jumbled up in his head.

Best not to remember sometimes.

His head was tired, heavy; he was falling asleep.

He dreamed about himself and Dad, sitting in the dinghy, rowing home from the tree house. A big boy with ginger hair stood on the towpath ahead, facing them, looking out over the water. The dinghy heaved through the water faster than ever before. Dad reached out with his oar and pulled them close to the bank. Dad climbed out of the boat and on to the grass. He said “Stay there,” but Ethan didn’t want to. Dad went over to the boy. Dad’s mouth was opening wide; he was shouting at the boy. But Dad’s words were silent. They didn’t make a sound.

Ethan scrabbled on to the bank. There was a thud. The boy was falling back, back, back on to the concrete. Thud. The big boy was lying there with blood on his face . . . the big boy wasn’t even moving. . .

Ethan woke with a jump. He sat up and grabbed a handful of quilt. He wasn’t in the little boat any longer. He was in his bed. His back was sweaty and he’d wriggled out of his cocoon. The clock on the wall said five past midnight. He turned on his lamp. It was OK. There was no ginger-haired boy lying there, in his cabin. His room looked the same as always.

Ethan lay back. He curled up in a tight ball like Merlin. What if the boy was dead? What if Dad had hurt him?

He shut his eyes. He was back at Deity after Dad said, “Run home.” Mum was on the sofa, sleeping. He stood watching, wanting to wake her and tell her about Dad and the boy. But his arm wouldn’t move because he was afraid to say the words out loud, and Dad always said “Don’t Get Mum Upset” because there was a baby called Maisie in her tummy that had tried to be born early. And when Dad got back that night he didn’t tell Ethan what had happened, he just came into his cabin and said, “Let’s not tell Mum about that boy”. And Ethan didn’t speak again after what he’d seen. And he didn’t speak the next day either. He felt too sick. And if he did speak, he might tell someone and Dad might get in trouble.

Dad didn’t talk about the boy again. And then Maisie was born too early and she died. Mum was always crying, and when Ethan tried to think about why he’d stopped speaking, his head was foggy.

Ethan opened his eyes. He had to tell Polly what he had remembered.

Sometimes it’s best not to remember, Ethan. Sometimes it’s best to leave the past behind. That’s what Dad had told him, and now Ethan knew why.

Dad didn’t want him going off at night, but everything in Ethan’s head was all mixed up like muddy water and the water wouldn’t clear. He had to make sense of his memories. Ethan put on his fleece and pulled his cords over his pyjama bottoms. He found his trainers on the floor. He took his torch from the hook beside his bed and turned it on. He climbed the cabin stairs and stepped out on to the stern deck.

The frosty grass crunched as he ran. There wasn’t time to look up at the stars tonight. He had to get to Polly.

He was out of breath by the time he got to Moon’s End. He knocked on Polly’s window that overlooked the bank and he waited, but she didn’t pull back the curtain. What if Polly didn’t wake up? He’d have to turn around and go back to his cabin, but he wouldn’t be able to sleep, he’d just lie there remembering the nightmare. He knocked again, harder this time, and the glass hurt his knuckles. A light went on. The curtain pulled back and Polly’s white face looked out. She opened her window.

“Ethan, what is it?” she said. “What’s wrong?”

He pointed to Moon’s End’s bow.

“I’ll let you in.”

Polly was wearing white pyjamas. He followed her through the lounge and the kitchen and into her cabin opposite the bathroom. On her bed was a quilt with coloured butterflies, but he was too dizzy to notice the rest of the room.

Polly reached over and touched his cold hand.

He pulled out his notebook and told her.

I had to help Dad today.
Sorry.

“Don’t worry. Are you OK?”

I remembered.

“Remembered what happened at the tree house?”

He nodded.

“And why you stopped speaking?”

Ethan shrugged. He didn’t know for certain.

Maybe.

“Sit down,” she said gently.

Ethan sat on her butterfly bed.

“It’s OK,” Polly said. “Take your time. You don’t have to tell me until you’re ready.” Ethan nodded. He looked down at his notebook. He was scared, but he had to tell Polly. He couldn’t keep it to himself any longer.

He wrote one word on each line: the words might not look so horrible if he wrote each one alone.

I
Think
Dad
might
have
hurt
a
boy

He looked up at Polly. She just looked back at him; she didn’t say anything. He needed her to say something. He wrote again. In sentences this time, so she could see it properly. See how terrible it might be.

I think Dad might have hurt the boy who wrecked the tree house. The boy fell and couldn’t move.

Polly looked down at the words.

“Are you sure?” she said at last. “But he’s your dad. He loves you. I know he gets a bit cross, but do you think he’d do that?”

Ethan didn’t want to think it could be true. But his brain kept swirling with memories: the boy’s face all scrunched up as he staggered back. Dad’s eyes swimming with panic. How still and white the boy’s face was as Dad said, “Run home.”

Why couldn’t Ethan remember what had happened before that?

“You don’t know exactly what happened, do you?” said Polly.

Ethan shook his head.

“We have to find out,” said Polly. She didn’t look afraid. “We have to find out exactly what happened, tomorrow.”

He nodded, but he didn’t understand what Polly meant. How could they find out?

“We have to go to the library,” she said. “They’ll have old newspapers from years back. We can look through them. I did it for a school project once.”

Ethan was scared of looking for the truth. But he didn’t feel quite so dizzy now that he’d told Polly.

He turned to a new page.

Can I sleep here tonight?

Polly nodded. She took a pillow and some cushions from her bed. She lay the cushions on the floor, and then she lifted her butterfly quilt and spread it over them. Polly had made him a bed.

Ethan knelt on the cushions and climbed under the quilt.

Polly opened a cupboard and brought out a blanket. She got into her bed and turned out the bedside lamp.

“Go to sleep,” she whispered.