At last, a question Charlie understood. Simon had described the murder scene to her within minutes of seeing it himself, which made it all the more frustrating that he was now keeping things back. “If he changed his mind, why did he?” she asked. “And if he didn’t, if he was never going to stab Blundy . . .”

“Go on,” Simon urged. “What you’re about to say could be important. I’m thinking the same thing, but I need to hear someone else put it into words.”

“That’s what I’m struggling to do, because it’s so . . . odd,” Charlie said. “If he never intended to stab Blundy, then he must have brought a knife and knife sharpener to the scene for some other reason. What could that reason be?”

“Go on.”

Charlie doubted she’d get a favorable response if she said, “Er . . . that’s it.”

“Also, he could have murdered Blundy in any number of ways, if he’d decided against stabbing,” she said. “Once he’d taped him into his chair, he could have strangled him, or clocked him over the head several times with the knife sharpener. If he’d wanted to suffocate him, he could have just taped over his mouth and nose—with tape! Why tape a sharp knife against his mouth and suffocate him in an unnecessarily convoluted way? It’s the weirdest thing I’ve ever heard.”

Simon was nodding. “At a rough guess, it would have been maybe five times quicker to shatter Blundy’s skull with the knife sharpener. Hannah, Blundy’s wife, was two floors down in the basement kitchen. She could have come up at any time. Killing Blundy as quickly and efficiently as possible would have increased the killer’s chances of getting in and out without being seen. Instead, he did the opposite.”

“You’re assuming the wife didn’t do it?”

Simon looked caught out. “You’re right.” He sighed heavily. “I shouldn’t assume that.”

“I wouldn’t,” said Charlie. “If she didn’t kill him, that means someone else gained access to the house without either breaking in or ringing the doorbell, created a theater set of a murder scene at his leisure, offed Blundy, then escaped undetected. How likely is that? Though I suppose if we apply Occam’s Beard . . .”

These last two words made Simon wince whenever he heard them, including now. Occam’s Beard was Charlie’s pet name for the law that seemed to apply to nearly all of his cases: the simplest explanation is never the correct one. It was the opposite of Occam’s Razor. Charlie thought it was one of her greatest inventions, and was secretly hurt that Simon refused to recognize it or mention it by name.

“I don’t think Hannah Blundy did it,” he said. “Having said that, I reckon I’ve never been more likely to be wrong. She’s very . . . intense.”