“What – er –” Max was looking for a subtle way to ask the question, but had to give up “ – why do you have a houseplant with you?”

“A little keepsake, mon lapin!” said Marguerite, waving an enthusiastic fork. “It’s from the convent. It’s to stop me feeling homesick.”

“Oh.” Max considered this. “Does it work?”

“The right amount,” said Marguerite. “I don’t want to not be homesick. I like my home. But I don’t want it to stop me going places. You do whatever you have to do to get past it.” She pointed the fork at Max. “I know you’ve had the same trouble, mon lapin, and you’re doing well. That notebook of yours – I don’t know what you’re writing, but it’s working. Keep doing it.”

Max nodded, wondering what Sister Marguerite would say if she knew that Max was writing a suspect list for her investigation into an international diamond-smuggling operation. “I will,” she said.

After that Marguerite mostly told unlikely stories about the nuns in her convent, which were so funny that Max began to relax. Before she knew it, it was almost time to leave. Just for a few minutes, she stood at the front of the station, soaking up the crowds chattering in German and the lit-up restaurants and hotels and the wide roads and the bustle of Munich at night. The fresh air was steadying, and the mysterious sounds of German were exciting. Even though Max’s stomach knot was still there, the balloon of excitement in her chest was back too, and they were in a tug of war inside her.

Sister Marguerite tapped her shoulder. “Come on, Max, we’ll miss the train. You can have all day in Budapest tomorrow.”

“I think I’ll come back to Munich one day,” said Max, yawning.

“Good plan,” said Sister Marguerite, and she flapped her habit encouragingly in the direction of the train. So Max took one last swallowing-up look at Munich, then followed her inside.

Max had expected that a sleeper train would be enormous, but the Kálmán Imre was very small indeed. A tiny corridor led to even tinier rooms, that Sister Marguerite called “couchette cars” – little rooms with six bunks for sleeping on (“They’re called berths,” said Marguerite, “like on a ship”). The berths folded out from the wall, a stack of three on each side, and could be turned back into seats again; there were straps at the side of the middle and top ones, to stop you falling out, and a pile of white sheets and brown rug waiting on each. The car was so small that only one person could stand in it at a time, so they all had to queue to stash away their luggage and make their beds, then lie down to make way for the next person.