Max was on a middle berth. There wasn’t quite enough space to sit upright. She tucked her notebook under her pillow, wrapped herself up tightly in her brown rug, and watched as Sister Marguerite made a marvellous mess of putting sheets on the berth below.

“Are you finished yet?” barked a voice from behind.

The voice was speaking French, which was strange, because Max could have sworn it was the elderly German foghorn lady from the first train. Her voice was difficult to mistake. It was a thunderous croak, as though a frog had been given a megaphone.

“Just a moment,” said Sister Marguerite cheerfully.

“There have already been moments,” said the voice. “We have been here for so many moments that I can feel my skin wrinkling as I wait.”

Sister Marguerite turned around to see the speaker, and accidentally (or was it?) spun the sheet as she twisted and somehow got it tangled up in her own habit. “Goodness,” she said, “what active wrinkles you must have. I hardly ever notice mine. Oh dear, look what I’ve done.”

Max craned round past her to see the speaker. It was the same woman. She had a remarkably triangular face – a perfectly normal forehead that ballooned out into a huge jaw – and below that she was a bundle of furs and jewels. Her elbows and knees stuck out to the sides, so that she walked in a sort of wide squat, which put Max in mind of a scuttling crab. In one hand she clutched a bag of pear drops, and in the other, a smart black walking stick, which she tapped against the ground with an impatient click-click-click.

Behind her loomed an enormous young man, his face squashed into a permanent expression of menace. Max was worried that he might turn that menace on Marguerite, but to her astonishment, he chuckled boyishly at her instead. “Let me help you there,” he rumbled. Like the woman, his French was perfect, but they both had an accent that Max couldn’t quite place.

“Thank you, Mr—”

“Grob. Klaus Grob. Call me Klaus. And this is Ester.”

“Thank you, Klaus. I’m Sister Marguerite. This up here is Max.”

Max waved from her berth.

“ARE YOU FINISHED YET?” croaked Ester.

“Nearly! Now, Klaus –” and Sister Marguerite paused mid-tuck, innocently, while an explosive tut erupted behind them “– is that a Swiss accent you’ve got?”

Of course! Switzerland has three official languages – German, French and Italian. That explained their switch from German to French. Max hugged her rug a little tighter. If only all her investigations could be conducted lying here in bed.

“It is! Very good!” exclaimed Klaus, with genuine delight.

“But very irrelevant,” added Ester, “to the task at hand.”