“I’m just playing devil’s advocate here, trying to construct the sort of theory that a hostile person might. It might be seen as an unfortunate coincidence that you worked for the company run by your husband’s lover.”

“It wasn’t a coincidence,” I said. “And she wasn’t his lover. I was working there to prove that. Or to find the truth.”

“I mean, how would you really do it?”

“What?”

“Kill two people and make it look like an accident.”

“I thought you were talking about Frances Shaw.”

“We’ll come to Frances Shaw. I was thinking about the car. How would you do something like that? Tamper with the brakes, the way they do in films?”

“How do you tamper with brakes?” I said. “Anyway, what would that do, driving in London? You don’t kill two people driving along at thirty or forty miles an hour. At least, not reliably.”

“Sounds right,” said Ramsay. “So what do you do?”

I broke the promise I had made and made myself think about the event once more as I had hundreds of times before.

“They would have to be already dead. And you drive them to somewhere quiet . . .”

“Like Porton Way,” said Ramsay.

“That would be a perfect choice,” I said. “Where you can steer the car over the edge, set fire to it and then get away.”

“Making sure you don’t leave any traces,” said Ramsay. “Or drop anything.”

“Do you think I’d have left my scarf behind if I’d committed the murder?”

“You wouldn’t believe what people leave at murder scenes. False teeth. Wooden legs. I’m sure it’ll never come to this, Ms. Falkner, but if you’re ever called upon to construct a defense, I wouldn’t stress the point that leaving evidence at the scene is an argument that you weren’t there.”

“I was there. I went later.”

“Obviously the case with Frances Shaw is very different. Traces of your presence were found everywhere at the scene, including on the body.”

“I worked there,” I said, “and I pulled the body clear. I wasn’t sure she was dead.”

“That’s what the emergency services are for,” said Ramsay. “They can revive people who might seem completely dead to civilians like you and me.”

“She was dead.”

“I believe this argument has been had before. My point was that there’s no doubt you were there, even though you fled the scene. But while there’s obvious motive for you to kill your husband and his lover, even though you couldn’t have done it, there’s no motive at all for you to kill Frances Shaw, is there?”