When they got home, Malcolm went straight up to his room. He opened the door, and rushed over to the chinchilla cage. He took off the top of the box, opened the door of the cage, and then shut it again. And then turned round to see his family coming into his room.

“Oh!” said his mum. “Chinny looks amazing!”

“He looks so well!” said his dad. “Like he’d never even left his room!”

“Yes! Exactly like he did before!”

“Mr Braden is clearly an amazing vet,” said Malcolm.

“Yes!” said Jackie.

“He could probably operate on people.”

“Well, I don’t know about that,” said Stewart.

“I do,” said Malcolm.

Stewart frowned, but then Jackie said: “OK, everyone. It’s been a very tiring day. And night.” She checked her watch. “Five-thirty am. Time, definitely for bed.”

Ten minutes later, after he’d brushed his teeth and put his pyjamas on, Malcolm looked up at his parents from his bed. They looked back at him, their faces full of love and relief. In the corner of his bedroom, Chinny was running on his wheel.

“Will that stop you getting to sleep?” said Stewart. “We can take the wheel out if so.”

“No,” said Malcolm. “I like the sound of it.”

“So …” said Jackie, “we haven’t even asked. Did you have a nice time on the farm?”

Malcolm closed his eyes. “Yes. I did. I really did. Thanks so much for sending me.”

“And …” said Stewart, carefully, “that thing you said at the vet’s. Is that true?”

“Which bit?” said Malcolm.

“About the chinchilla. When you said, ‘he’s my pet and I love him …’”

Malcolm opened his eyes again. He was glad that had been his dad’s answer.

Because not everything he had said at the vet’s had been true. When he’d woken up from the anaesthetic, and discovered he was a boy again – which was only two seconds before his family had come in and seen him on the operating table – Malcolm had had to think very quickly.

He had thought very quickly, and decided, very quickly, to make up the thing about staying on the bus – and pretend that he had put Chinny into the box. Because Chinny wasn’t there – had never been there. Chinny had been looking out of Malcolm’s bedroom window the whole time.

Malcolm wasn’t a boy given to making things up. But in this particular case, he’d decided there was no point in trying to tell his family what had actually happened. They just wouldn’t believe him. No one, he knew, would ever believe him.

He knew he shouldn’t lie, under normal circumstances. But these were not normal circumstances.

And: one part of it had not been a lie. The last, and most important part: the part that his dad was asking him about now. It would’ve been a lie only three days ago, but now he could feel how true it was.

“No, Dad. I do really love Chinny.” And just to reiterate that, he turned to the tiny creature, who’d stopped running for a second on his little wheel, and said: “Te amo, Chinny.” At which point, Chinny seemed almost to nod … almost to smile … and then just started running as fast as he could, making that wheel spin for dear life. “In fact,” said Malcolm, “I love all animals!!”

Stewart and Jackie turned to each other, with tears in their eyes again, but smiles on their faces too.

“TATUFTB,” said a voice in the doorway. Everyone looked round.

It was Grandpa.

“What does that mean?” said Libby, poking her head round the door, with a toothbrush in her mouth.

“That’s a turn-up for the books,” said Grandpa.