There was a silence. Not a very encouraging one. It sounded impossible. But then, it had already been impossibly stolen twice. That still puzzled Max. “What I don’t understand,” she said, breaking the silence, “is how it was stolen in the first place. From Fort Vaults, and again from Sirkeci station.”

Rupert cheered up a bit at that, and pushed his glasses up his nose importantly. “That’s where a professional con man can help you, Max. Piece of cake. The Fort case is a very simple matter of diversion. There’s no way in without setting the alarms off. So, you set them off. You make a big show of it. You let them arrest someone. Meanwhile, while they think they’re catching the thieves, the real thief is somewhere else entirely, and no one notices. You saw in the papers, perhaps, that there was another break-in at Fort the week before they noticed the diamond had been switched for a fake? Yes? I’d bet any money that the Phantoms set that up. Then all Suzanne has to do is turn up dressed as a policewoman or security guard, and while all the confusion is going on, replace the real diamond with the fake one.”

Max thought about the alarms at Great-Aunt Elodie’s house. Her mind, as sharp as her own great-aunt’s, set to work.

“I’d love to know what they used to make the fake,” Rupert added. “It must have been good. Maybe glass, or quartz – maybe cubic zirconia, that’s very fashionable … but the police are holding it very close to their chests. Probably don’t want to admit that they were so easily fooled!” He cough-chuckled to himself, wheezing merrily, then caught his breath and continued. “Anyway. As for the theft at the station: obviously, tripping up Marguerite was a deliberate distraction. But there’s a few ways to pick a pocket, and I don’t know which she used. Did she touch the diamond, Max?”

“Yes. And –” Max suddenly remembered “– she took something from my case, I think.”

“What did you have?”

Max recited everything she had packed. Rupert looked puzzled.

“Frankly, Max, that doesn’t really help…”

“Oh!” said Max. “And there were the things Sister Marguerite left behind. Tickets, and a newspaper, and glue, and a jar, and a bag of thread…”

Rupert’s eyes lit up. “Aha! The spider trick, then.”

Across the table, Ester moaned and shut her eyes.