“Yes. Again, I have pictures. But the important thing is that after that, I don’t think he did anything at all. At least until he broke into my room and threatened to shoot my wife in the spine.”

The DCI winced. “Ooh, good detail.”

“I deny it entirely,” insisted the professor.

“Aye, and you can carry on denying it at the station.” The DCI turned back to Liza, and she almost thought he looked encouraging. “So, what do you think happened to everybody else?”

This was the home stretch. It was a sketchy home stretch, and Liza wasn’t sure how far she’d have to follow it before she actually got home, but there was only really one way it made sense. “Well as you’ve pointed out many times, I don’t have much evidence. On the other hand, no offence, often you guys don’t either.”

“Excuse me.” The DCI scowled. “I’d watch what you’re saying when you’re one of the prime suspects in six murders.”

“Not like that.” Liza backtracked hurriedly. “I just mean that—and you know this—evidence in real crimes isn’t like in a detective story. Or I suppose it is like the evidence in a detective story, and that’s the problem: there’s loads of different ways to interpret it, and there’s no one guy with a funny hat or a silly moustache who can say that it has to be this way and can’t be any other. Most people are convicted on circumstantial evidence because most evidence is circumstantial.” She was worried she was losing the detective’s sympathy, so she tried again. “For Lady Tabitha, the only person with any reason to kill her was her nephew—Sir Richard gambled constantly, and he’s bound to inherit something now she’s gone.”

“Excuse me,” put in Sir Richard, “what about her secret granddaughter?”

The DCI gave a begrudging nod. “He’s got a point.”

“I mean … it’s possible. It just seems incredibly unlikely. Plus, I heard the pipes making a weird noise the night she died, which I’m pretty sure was him showering off the blood. He’s the only one whose shower made quite that sound.”

Sir Richard was looking outraged. “How dare you suggest—”

“And it is just a suggestion.” Liza tried to sound mollifying. “Maybe I’ve got it all mixed up and it was actually, I don’t know, that kid who just took a holiday job here.”

“Quinn,” the kid reminded her.

Liza gave Sir Richard a look. “I just think—you had the opportunity. If I’m right about how the money shakes out, then you had motive. And after she died you got really keen on the, ‘It’s one killer who isn’t me,’ theory. And it’s always the family.”

“So what about the colonel?” asked Ruby guardedly.