“Why not, indeed. Good question, Lady Georgiana. And they weren’t the only substances found. It seems there was atropine from eyedrops and certain other chemicals in his system too. So either he was a hypochondriac who administered various treatments to himself, or someone fed him a deadly cocktail. The MO reckons that he wasn’t in the best condition—lungs damaged by too much smoking, heart not too strong—and thus it was the combination of substances, coupled with a brisk walk on a very cold morning that killed him. Rather ingenious in a way, although surely the killer realized that the substances would show up in his tissues.”

“Perhaps the killer thought the death would be taken as a heart attack,” Darcy suggested.

“And probably would have, Mr. O’Mara,” Fairbotham said, “if someone hadn’t chosen to plunge a great, big knife into his back while he lay there.”

He looked up as one of his men came in. “What is it, Finch?” he asked.

There was a muttered conversation then Fairbotham turned back to us. “It seems that we’ve found our cyanide in a photographic darkroom.”

“That was my son’s darkroom,” Edwina said. “He was much interested in photography.”

“Fingerprints were found on the bottle,” Fairbotham said, “and we’ll be comparing them to the prints we took earlier from everyone here. And, Your Grace, I’d appreciate it if you let me take a look at your medicine cupboard and showed me your heart medication.”

“Certainly, Chief Inspector,” Edwina said wearily. She led him from the room. She reminded me of a splendid balloon that is slowly deflating. I wondered how many more of these unpleasant surprises she could take. And how she’d handle it if the culprit turned out to be a member of her family.

Princess Charlotte rose with effort to her feet first. “I could do with some coffee. All these shocks are not good for the system.”

Virginia stood too. “There will still be coffee in the morning room. Maybe Mr. O’Mara will accompany us to protect us and cheer us up. There has been far too much gloom and doom in this household recently.” She fluttered her eyelashes at Darcy in what she thought was a sexy manner. Darcy was gracious enough to offer her his arm, and led her out of the room.

I stood alone in the deserted room, trying to think. A clever cocktail to induce a heart attack—surely none of the people present had a sufficient knowledge of chemicals to concoct such a thing? It had to be an outsider. But who? And why?