“Shoot,” Bertha said, bracing herself for an interruption from Sellers.

“Apparently Sally had been peeling potatoes. She’d gone down to the cellar to get some onions to mix with them. She was carrying a dish pan with some peeled and some unpeeled potatoes in it. She was also carrying a big carving knife in her right hand. She evidently stubbed her toe and tripped on the top of the stairs and fell all the way down, running the knife through her chest.”

Bertha became absorbed in the telephone conversation. “Anything that makes it appear death wasn’t accidental?” she asked.

“Well, yes.”

“What?”

“The colour of the body.”

“What’s that got to do with it?”

“The police say it indicates carbon monoxide poisoning.”

“Go on.”

“I gather they think the knife may have been pushed into her body immediately after her death, instead of being the instrument which caused that death.”