“You really believe that there just happen to be multiple murderers running around the hotel at the same time?” Sir Richard asked. Condescension was slowly giving way to incredulity. “If you don’t mind my saying, that feels rather fanciful.”

Ruby fixed him with a glance that, even on zero sleep, managed to be icy. “Whereas your theory that we’re being hunted down by a mysterious avenging angel is, of course, the kind of thing that happens every day.”

“It’s a simple question of mathematics.” Apparently, Sir Richard was standing firm on this one. And for a distracted moment Liza let herself wonder whether it was a matter of pride or if he had some other motivation. “It’s exponentially less probable that multiple people would have chosen to commit murder simultaneously than that one very, very bad murderer just happens to be in the hotel.”

Part of Liza wanted to avoid engaging. Sir Richard didn’t seem in a receptive mood, and challenging an irritable man with a gun seemed like a good way to get shot. But on the other hand, he was a noted amateur sleuth, and that meant he might have something interesting to say. “So, who do you think it is? This single phantom killer?”

Sir Richard steepled his fingers. “Ah, I confess I do have a rather nice little theory on that.”

“Do tell.” Ruby’s voice was the clearest example of dripping with sarcasm Liza had ever heard.

“It’s the maid,” said Sir Richard smugly.

“Which maid?” asked Liza.

“There’s only one,” Ruby replied. “I think she and the footman might have had a thing going.”

Liza let her head collapse into her hand for a moment. “Tell me you didn’t have sex with her as well?”

“Not getting jealous, are we?”

“As the lady says,” Sir Richard butted back in, “there’s only one maid, and I think she may be behind all of it.”

“All of it?” To Liza, at least, that seemed on the very low end of probability.

“I don’t know why you’re so shocked. It was you who put me onto her. You were right, you see—Aunt Tabitha had been squabbling with Mrs Ackroyd just before Belloc was shot. And when I dug into that a bit, it turned out that the maid was what they’d been squabbling about.”

That did tally with what Liza knew. She just wasn’t sure it all added up to four murders.

“I don’t suppose”—Hanna stirred sleepily on the sofa—”that while you were digging up all this information you bothered to find out what this young woman’s name was, did you?”

Sir Richard looked perplexed. “Should I have done? Didn’t seem terribly important. Anyway, she’d also apparently had a bit of a run-in with Mr Ackroyd. The footman even confronted him on her behalf.”