“Sorry, buddy. This oral menstruation’s a bitch.”

“Jesus, Al!”

He shrugged. “If you can’t joke about it, what’s the point of anything? Now where was I?”

“Butterfly effect.”

“Right. It means small events can have large, whatchamadingit, ramifications. The idea is that if some guy kills a butterfly in China, maybe forty years later—or four hundred—there’s an earthquake in Peru. That sound as crazy to you as it does to me?” It did, but I remembered a hoary old time-travel paradox and pulled it out. “Yeah, but what if you went back and killed your own grandfather?”

He stared at me, baffled. “Why the fuck would you do that?” That was a good question, so I just told him to go on.

“You changed the past this afternoon in all sorts of little ways, just by walking into the Kennebec Fruit . . . but the stairs leading up into the pantry and back into 2011 were still there, weren’t they? And The Falls is the same as when you left it.”

“So it seems, yes. But you’re talking about something a little more major. To wit, saving JFK’s life.”

“Oh, I’m talking about a lot more than that, because this ain’t some butterfly in China, buddy. I’m also talking about saving RFK’s life, because if John lives in Dallas, Robert probably doesn’t run for president in 1968. The country wouldn’t have been ready to replace one Kennedy with another.”

“You don’t know that for sure.”

“No, but listen. Do you think that if you save John Kennedy’s life, his brother Robert is still at the Ambassador Hotel at twelve-fifteen in the morning on June fifth, 1968? And even if he is, is Sirhan Sirhan still working in the kitchen?”

Maybe, but the chances had to be awfully small. If you introduced a million variables into an equation, of course the answer was going to change.

“Or what about Martin Luther King? Is he still in Memphis in April of ’68? Even if he is, is he still standing on the balcony of the Lorraine Motel at exactly the right time for James Earl Ray to shoot him? What do you think?”

“If that butterfly theory is right, probably not.”

“That’s what I think, too. And if MLK lives, the race riots that followed his death don’t happen. Maybe Fred Hampton doesn’t get shot in Chicago.”

“Who?”

He ignored me. “For that matter, maybe there’s no Symbionese Liberation Army. No SLA, no Patty Hearst kidnapping. No Patty Hearst kidnapping, a small but maybe significant reduction in black fear among middle-class whites.”

“You’re losing me. Remember, I was an English major.”

“I’m losing you because you know more about the Civil War in the nineteenth century than you do about the one that ripped this country apart after the Kennedy assassination in Dallas. If I asked you who starred in The Graduate, I’m sure you could tell me. But if I asked you to tell me who Lee Oswald tried to assassinate only a few months before gunning Kennedy down, you’d go

‘Huh?’ Because somehow all that stuff has gotten lost.”

“Oswald tried to kill someone before Kennedy?” This was news to me, but most of my knowledge of the Kennedy assassination came from an Oliver Stone movie. In any case, Al didn’t answer. Al was on a roll.

“Or what about Vietnam? Johnson was the one who started all the insane escalation.

Kennedy was a cold warrior, no doubt about it, but Johnson took it to the next level. He had the same my-balls-are-bigger-than-yours complex that Dubya showed off when he stood in front of the cameras and said ‘Bring it on.’ Kennedy might have changed his mind. Johnson and Nixon were incapable of that. Thanks to them, we lost almost sixty thousand American soldiers in Nam. The Vietnamese, North and South, lost millions. Is the butcher’s bill that high if Kennedy doesn’t die in Dallas?”

“I don’t know. And neither do you, Al.”

“That’s true, but I’ve become quite the student of recent American history, and I think the chances of improving things by saving him are very good. And really, there’s no downside. If things turn to shit, you just take it all back. Easy as erasing a dirty word off a chalkboard.”

“Or I can’t get back, in which case I never know.”

“Bullshit. You’re young. As long as you don’t get run over by a taxicab or have a heart attack, you’d live long enough to know how things turn out.” I sat silent, looking down at my lap and thinking. Al let me. At last I raised my head again.

“You must have read a lot about the assassination and about Oswald.”

“Everything I could get my hands on, buddy.”

“How sure are you that he did it? Because there are about a thousand conspiracy theories.

Even I know that. What if I went back and stopped him and some other guy popped Kennedy from the Grassy Hill, or whatever it was?”

“Grassy Knoll. And I’m close to positive it was all Oswald. The conspiracy theories were all pretty crazy to begin with, and most of them have been disproved over the years. The idea that the shooter wasn’t Oswald at all, but someone who looked like him, for instance. The body was exhumed in 1981 and DNA tested. It was him, all right. The poisonous little fuck.” He paused, then added: “I met him, you know.”

I stared at him. “Bullshit!”

“Oh yes. He spoke to me. This was in Fort Worth. He and Marina—his wife, she was Russian—were visiting Oswald’s brother in Fort Worth. If Lee ever loved anybody, it was his brother Bobby. I was standing outside the picket fence around Bobby Oswald’s yard, leaning against a phone pole, smoking a cigarette and pretending to read the paper. My heart was hammering what felt like two hundred beats a minute. Lee and Marina came out together. She was carrying their daughter, June. Just a mite of a thing, less than a year old. The kid was asleep. Ozzie was wearing khaki pants and a button-down Ivy League shirt that was all frayed around the collar. The slacks had a sharp crease, but they were dirty. He’d given up his Marine cut, but his hair would still have been way too short to grab. Marina—holy Christ, what a knockout! Dark hair, bright blue eyes, flawless skin. She looks like a goddam movie star. If you do this, you’ll see for yourself. She said something to him in Russian as they came down the walk. He said something back. He was smiling when he said it, but then he pushed her. She almost fell over. The kid woke up and started to cry. All this time, Oswald kept smiling.”

“You saw this. You actually did. You saw him. ” In spite of my own trip back in time, I was at least half-convinced that this had to be either a delusion or an outright lie.

“I did. She came out through the gate and walked past me with her head down, holding the baby against her breasts. Like I wasn’t there. But he walked right up to me, close enough for me to smell the Old Spice he was wearing to try and cover up the smell of his sweat. There were blackheads all over his nose. You could tell looking at his clothes—and his shoes, which were scuffed and busted down at the backs—that he didn’t have a pot to piss in or a window to throw it out of, but when you looked in his face, you knew that didn’t matter. Not to him, it didn’t. He thought he was a big deal.”