At each stop, people left, and could be crossed off. “Red hat” and “Has tiny dog”, for example, were gone at Strasbourg, and “Green hair” got off at Karlsruhe. The train really emptied out at Stuttgart: Max crossed off lots and lots of people, and made a little note next to Stuttgart on her map. By this time the two police officers had a lot less people to look importantly at, and as they tramped up and down, Max got the feeling that their hearts weren’t really in it. Max, on the other hand, was starting to get excited. With so few people left on board, the idea of catching the thief suddenly seemed much more real.

She traced her finger along the line from Paris to Stuttgart. She had well and truly left France. It wasn’t too bad on the warm bright train, speeding through the darkness. She only felt queasy when they pulled into train stations, dimly lit and alien, and she remembered that soon she would have to get back out again somewhere strange.

But then, each station also brought the fascination of finding out who would leave. By the time they pulled out of Augsburg, the stop before Munich, the train had almost emptied and her list had shortened dramatically.

There were several likely suspects on there, she thought. Her favourites were a fabulously well-dressed young woman in sunglasses; an elderly German lady in furs and jewels with a foghorn voice, who was travelling with a younger man built like a small mountain; two sharp businessmen with even sharper moustaches; and a bristled man in a raincoat clutching his suitcase very tightly. Some were so unlikely that she was almost tempted to cross them off – it probably wasn’t the family with three toddlers, or the young couple reading poetry to each other – but she was a thorough detective, and she couldn’t cross them off without good reason. After all, the thief could be hiding in plain sight by looking as ordinary as possible.

After her post-Augsburg headcount, she made her way back to her seat at last. Rupert still here, she thought. A lot of her favourite suspects were still on the train, in fact. The woman with the foghorn voice was still there, and as Max walked back to her own seat she was blaring angrily at the businessmen about something. The businessmen looked like they were trying not to cry. Max made a little note next to her: slightly terrifying.

“Find anything interesting?” said Sister Marguerite.

“Lots,” said Max. Marguerite nodded approvingly. Rupert just snored gently – he was asleep, wonkily restored glasses back on his nose. Max had to admit that he didn’t look like an international criminal.