Wren had been about to refuse, but the fact that she had never heard of the book he named made her hesitate. She’d been expecting him to ask about one of Anchorage’s treasures: the great illuminated Acts of the Ice Gods, or Wormwold’s Historia Anchoragia. She said, “Who on earth would want a whole book about tin?”

Gargle laughed, as if she’d made a joke that he liked. “It’s not about tin,” he said. “That’s what it’s made of. Sheets of metal.”

Wren shook her head. She’d never seen anything like that. “Why do you want it?” she asked.

“Because we’re burglars, and I’ve learned that it’s valuable,” said Gargle.

“It must be! To come all this way…”

“There are people who collect such things: old books and things. We can trade it for stuff we need.” Gargle hesitated, still watching her, and then said earnestly, “Please, Wren, just ask your father. Always nosing about in museums and libraries, he was, when I knew him. He might know where the Tin Book is.”

Wren thought about it as she drank the rest of the chocolate. If he had been asking her for the illuminated Acts, or for some treasured classic, she would have said no at once. But a book made of metal, one that she’d never even heard of… it couldn’t be very important, could it? It would probably never be missed. And Gargle seemed to want it very badly.

“I’ll ask,” she said doubtfully.

“Thank you!” Gargle took her hands in his. His hands were warm, and his eyes were rather lovely. Wren thought how nice it would be to tell Tildy that she’d spent the small hours of the night drinking cocoa in the cabin of a dashing underwater pirate, and then remembered that she would never be able to tell Tildy or anybody else about Gargle and the Autolycus. That made it even nicer somehow. She had never had a proper secret before.