His eyes narrowed. “I think you are who you say you are, which isn’t something I think about everybody else.”

Hanna, apparently torn between not wanting to take Ruby’s warnings at face value and not wanting to take the vicar at face value either, gave Reverend Lincoln a challenging look. “Okay, so what do you want to tell us?”

“People confide in me,” he began. “It’s part of the job.”

“Sorry,” Hanna told him, “atheist.”

“I’m not saying you should confide in me. But I’ve heard some things that might matter.”

“What things?” asked Liza, still cautious.

“This morning, Mrs Ackroyd came past my room, rather early. I thought it was unusual at the time. Later on, one of the maids told me that she’d heard her having some kind of confrontation with Lady Tabitha.”

That was another unnecessary complication. “Lady Tabitha?”

“It may be nothing, but … I thought you should know. As it happens, I agree with you that Mrs Ackroyd is the most likely suspect in both murders and, well, if she’s also engaged in something nefarious, you should be careful.”

“Tell me you’re not another one who believes in Belloc’s mystery mastermind.” Hanna’s tone was contemptuous.

Reverend Lincoln gave a good-humoured smile. “I’d have thought you’d expect me to believe in unusual things.”

“There’s a difference between supernatural and wacky,” Hanna replied. “Plenty of reasonable people believe in God, but I mean, come on—a mysterious criminal genius who goes only by a single initial and who, what, sends a bickering middle-aged couple to do his dirty work for him?”

It sounded implausible to Liza, but Reverend Lincoln just shrugged. “You might be surprised. I’ve seen all kinds of strange things in my parish. And there are plenty of middle-aged criminals in the world.”

“So … what?” Liza tried to lay this theory out logically. “Mr B hires two people to come up here and … do some crimes for some reason? Possibly to harass an old rich lady. Then one of them kills the other but still goes on harassing the old rich lady on her own time?”

The vicar was still wearing a mantle of endless patience. “You say that as if exploiting old rich ladies wasn’t something criminals did.”

He had a point. John George Haigh the Acid Bath Murderer had killed almost entirely for profit, and his victims had mostly been wealthy older people. “That doesn’t explain why she’d shove her husband off a balcony first.”

“And you say that”—he gave her a dry smile—”as if professional killers never fall out with each other.”

At this, Hanna could barely contain her laughter. “You think the Ackroyds were professional killers?”

“I think professional killers don’t always look the way you think they will.” Reverend Lincoln’s tone was grave. “That’s part of what makes them good at their job.”