In “11/22/63,” we get glimpses of a nimbus of evil that surrounds the world. There are no single crimes. Each act of cruelty or violence is somehow associated — harmonized, King would suggest — with every other act. Inside the past, Amberson learns there are no accidents, no inadvertencies. Just an infernal machine. (Tick, tock.) He says: “Coincidences happen, but I’ve come to believe they are actually quite rare. Something is at work, O.K.? Somewhere in the universe (or behind it), a great machine is ticking and turning its fabulous gears.”

There is a darker what-if. What if history is too forceful to redirect? What if jiggering the engine produces no favorable outcome — merely a postponement of the inevitable? If he had lived, Kennedy might not have escalated the war in Vietnam, and might have kept America out of a bloody mire. But we don’t know.

Oswald just happened to be at the right place at the right time. He and his wife were effectively done, and she was living with Mrs. Paine out in Irving. He used to come on the weekends, but that week, he came on Thursday — the night before the assassination. And it seems pretty clear from his actions and from the things he said that he had decided to do this, but that he could be persuaded to change his mind. He and Marina went to bed that night and in bed, he asked her, “Is there a chance that we can get back together?” And she was very cold to him. She said, “No, I don’t think that’s ever going to happen, Lee.” And in the morning, he left his wedding ring and he left all the money in his pockets in a teacup in the kitchen for her. And that was it. There is this chain of ifs, but really, it’s as simple as that. He wanted to shoot somebody. He wanted to be somebody famous. It’s all there. The pieces all click together pretty nicely.

And with that he’s off again. Of Salman Rushdie, who once gave him a terrible review in the New York Times, he says: “That flaccid fuckhead. He was detestable. I called up the Ayatollah, nobody knows that.” Roald Dahl: “The cruelty in his books is off-putting. Scary guy. I know he’s very popular but what’s nice about this guy? He’s dead, that’s what’s nice about him.” Stephen King: “Bullshit.” Gwyneth Paltrow: “I can’t stand her.”

Over the three-day course in Wales, my scepticism drained away entirely and I became a Hare devotee. I think the other sceptics felt the same. He was very convincing. I was attaining a new power, like a secret weapon. I felt like a different person, a hardliner, not confused or out of my depth as I had been when I’d been hanging around with Tony in Broadmoor. Instead, I was contemptuous of those naive people who allowed themselves to be taken in by slick-tongued psychopaths.

My mind drifted to what I could do with my new powers. If I’m being honest, it didn’t cross my mind to become some kind of great crime fighter, philanthropically dedicated to making society a safer place. Instead, I made a mental list of all the people who over the years had crossed me and wondered which of them I might be able to expose as having psychopathic character traits. Top of the list was AA Gill, who had always been very rude about my television documentaries and had written a restaurant column in which he admitted to killing a baboon on safari.

“Item 8 Callous/lack of empathy,” I thought, and smiled to myself.’

So her father was a hack?

“My father,” she said, “was a literate, sophisticated, erudite man.”

He was?

He loved Dickens, she said. “He was a great Joycean.”

He was?

“He corresponded with F. Scott Fitzgerald. He had aspirations to be that kind of writer.”

She seemed uncertain where to go with this.

Finally: “He hated the Hardy Boys.”