The car was full, and loud with the sound of six people sleeping. Max hardly dared breathe. Everyone had huge cases, and there wasn’t quite enough room so Rupert had been forced to stuff his case at the bottom of his bed. It was very large, so he was almost folded double. Max eased it out very, very slowly.

Rupert snuffled, rolled over, bumped into the wall, and murmured some aggrieved English in his sleep.

Heart thumping, Max opened Rupert’s case.

It was empty. No spare clothes. No toothbrush. Nothing. His jacket pocket held his tickets (Max checked: all the way to Istanbul), his passport, some money, his little paperback book, and his wonky spectacles.

Why travel with an empty suitcase? Surely that was odd? Max couldn’t see how it helped, but it was strange enough to feel important. Better than Klaus’s socks, anyway.

Rupert had started murmuring again, so Max crept back to her berth, and finished her notes under her rug. Huge empty case, she wrote, and after a moment’s thought she added, Leaving room for something? But what? The diamond was tiny.

There was nothing more to do, but her heart was still pounding, as if she might somehow still get caught. She hugged her notebook closely, and ran over what she had seen in her mind, searching it for any missing clues. By the time her heart had slowed down and she began to drift off, there was a slight silver tinge around the edges of the curtain.

She was almost asleep when Sister Marguerite rolled over, sending the houseplant to the floor with a thump. Max’s eyes jumped open.

Sister Marguerite.

Technically – technically – there should be one more name on her list of passengers that had boarded both trains. It did seem a bit unlikely. But then, everything about Sister Marguerite seemed a bit unlikely.

Max didn’t want Sister Marguerite to be the thief. The thought set her homesickness off all over again. But the idea wouldn’t let go of her. That is the trouble with ideas that you have before dawn: they are extra sticky.

She would have to just check, she decided, and then she could forget about it.

She crept down the ladder, pulled Sister Marguerite’s bag out from under the bed, and put in a hand. Tickets. Money. Tissues. A book.

Of course, Le Goff had already checked the bag, but there was still the mysteriously endless habit. She folded it out, and checked its pockets. Crisps. The now-squishy banana. An umbrella. String. Flea spray. Mittens. Something cold and hard…

Max felt sick as she ran a finger along the cold-hard-something. That was definitely a gun.

She drew it out to take a look. It was a very dainty gun, small and pretty, but still very much a gun.