“Just a shadow, really.” Professor Worth looked like he was trying to hide inside his own jacket. “I thought it was a person, but really, it was probably a—a cat or something. Or a bird. There are very big birds in this part of the country, aren’t there?”

There might have been, but it seemed unlikely to Liza that anybody would mistake a bird, however big, for an intruder.

Colonel Coleman lowered his pistol and addressed the room. “Well, what do you say we go and look anyway? If the filthy bounder behind all this really is skulking around outside fellows’ windows, we should go and see him off.”

On the one hand, running around in the dark looking for an intruder who had at least a couple of minutes’ head start and could have gone in literally any direction seemed unlikely to be fruitful. On the other hand, giving up without a chase felt wrong on several other levels. Besides, there was still snow on the ground, so if there had been a prowler poking around there would probably be tracks of some kind to follow. “Come on then,” said Liza. “Two groups of three again?”

Ruby gave a cold smile. “Boys versus girls?”

“I might sit this one out, actually.” The professor was staring into the middle distance and talking to nobody in particular. “Had a bit of a scare. Made rather a loud bang. Spooked myself.”

“Then that settles it,” said Ruby despite the fact that it didn’t actually settle anything. “I’ll go with the ladies, the three remaining gentlemen will go with each other, and we’ll try not to shoot one another in the dark.”

And with the inevitable momentum of a decision made, that was how they arranged themselves. The six investigators walked together out of the front door of the hotel and around to the east wall, where, sure enough, climbing ivy led up to a lighted window. The ground was strewn with broken glass, but the tiny, paranoid part of Liza that had taken to viewing every tiny detail of the case as a potential misdirect noted that it was possible the window had been broken from the outside and the glass thrown out afterwards. Not that there was any reason at all for anybody to do that; it would have been needlessly circuitous and entirely pointless.

Except all of this was pointless. Murder, at its heart, was a fundamentally pointless endeavour. And not for the first time in her career, Liza felt a tiny roil of uncertainty at her decision to devote her adult life to talking about it.