“It can’t,” Carmen had said grimly. It couldn’t. She couldn’t fit in with them and their travel and their knowledge, and their immediate acceptance of Sofia as one of them.

“Sorry,” said Oke kindly. “You look lost in thought. I didn’t mean to hit a sore spot.”

Carmen felt raw all over that morning, completely exposed and vulnerable.

“You didn’t,” said Carmen. She blinked. “I . . . I would have liked to have gone . . . I think. But at the time, I . . . I thought I couldn’t keep up. I failed my exams.”

“On purpose?”

“No! . . . Maybe,” she said. “If I didn’t try, then . . . I suppose I had an excuse for failing.”

Oke nodded. “I can understand that.”

There was a pause.

“This is the bit where you tell me all the best people didn’t go to university, and the University of Life is brilliant, and everything is going to be absolutely fine,” said Carmen.

“Where I am from,” said Oke, “there aren’t as many good options for people without an education, so no, I would never say that. But look at the good you are doing with your life.”

“I don’t know if I’m doing much good,” said Carmen.

“I think your mice are making people happy in the world. They make me happy!”

“I don’t think that counts; I like doing them.”

“It counts. Anyway, I need to order another book and I need to say thank you for the discount and the way I would like to thank you is with this!”

He brandished something at her.

“What’s that?”

It was a tourist flyer for Camera Obscura with a two-for-one offer, valid on a Tuesday morning, which it still was, for about forty minutes.

“Camera Obscura?” said Carmen, frowning. “I’ve heard of it. It’s a touristy thing, isn’t it? What even is it?”

“It’s how they used to draw things before photographs! It’s amazing.”

“Isn’t it for children?”

He rolled his eyes. “And the young at heart.”

“But what actually is it?”

“It’s a hole in the roof!”

Carmen frowned. “You want to go see a hole in a roof?”

“It changed the world!”

“How?”

“Because! You had perspective and straight lines and could draw and trace things and get precision into art and work and, well, it’s just very, very cool. It’s over twenty-five hundred years old. Don’t you think that’s quite cool?”

“That striped building by the castle?”

“Now you’re being dense on purpose. The technique.”

Carmen picked up the leaflet. It was covered in wacky light shows. “Why is it covered in wacky light shows?”

“That’s just to get the kids in,” he said. “But they have the original at the top. I think it’s worth seeing.”

“The original box with a hole?” Carmen frowned. “But we can still go see the wacky light show, right?”

“If you like.”