Assassination averted: the king of horror turns back time

11.22.63 by Stephen King. Hodder & Stoughton, 740pp, £14.99

As a geeky teenager I was fascinated by time travel. I loved the conundrums found in Planet of the Apes, Jack Finney’s Time and Again and Ray Bradbury’s famous short story A Sound of Thunder – so much so that I even had a go myself, writing a short story for English class in which an assassin uses a time machine to go back and murder the device’s inventor before he conceives of it, thus ensuring that time travel is never made possible. But the killer fails and the device falls into the hands of the inventor, leading him to . . . uh, well, you get the drift. (Hey, the teacher liked it.)

I get sense that Stephen King has long harboured a similar fascination with the notion of using murder to change the course of history. King says in the afterword to 11.22.63, his latest blockbuster, that he first thought up the idea nearly 40 years ago, when he was a publishing nobody, but dropped it because of the amount of research involved and because, frankly, "even nine years after the deed, the wound was still too fresh".

The deed, you might deduce from the title, is the assassination of John F Kennedy, and the protagonist of 11.22.63 is intent on stopping Lee Harvey Oswald before he can fire two bullets from the sixth floor of the Texas Book Depository Building in Dallas. It's not giving anything away to say that this scene provides the climax for King's doorstopper, but it takes a long time to get to that point – five years, two months and 13 days to be exact.

King’s hero (and idealised alter-ego) is Jake Epping, a divorced high-school English teacher in Lisbon Falls, Maine. Jake is a regular at Al’s Diner, whose owner long ago discovered a rabbit hole – a time portal – in the back of the restaurant. When you step through the rabbit hole, you’re back in Lisbon Falls on September 8th, 1958 at 11.58am. You can go back and forth through the rabbit hole as often as you want, but every time you return to the past the clock is reset – it’s always the exact moment of the same day. No matter how long you stay in the past, when you return to the present only two minutes have passed. Which explains why Al Templeton, whom Jake saw hale and healthy only the night before, is suddenly decrepit and dying of cancer.

Templeton has spent nearly five years in the past, determined to eliminate Oswald. But as death approaches, he passes the challenge on to Jake: change the past and maybe, just maybe, make the future a better place. Jake steps into 1958, beginning a long odyssey that takes him from Lisbon Falls to creepy Derry, Maine, which is reeling from a series of eerie child murders that King readers will recall from his novel It, to Florida and finally, Texas.

As Jake waits out Oswald’s return from the USSR with his Russian wife and baby daughter, he settles down outside Dallas, assumes a new identity and finds work as a school substitute. He becomes involved with the bucolic community and falls in love with a Sadie, a gawky but beautiful librarian (and smoker! How authentically retro is that?), who cops on that there’s something not of this world about her eccentric, secretive boyfriend.

11.22.63 has got it all. There's science fiction and "what-if?" alternative history; a horror story and psycho-on-the-loose thriller with a lot of the author's typical spook-show tropes; historical fiction; an offbeat romance; a Larry McMurtry-ish depiction of small-town Texas life; and King's own take on the enduring mystery of the Kennedy murder. Before Jake is willing to pull the trigger on the most famous assassin in history, he has to be convinced that Oswald really is a lone gunman and not the "patsy" celebrated by conspiracy cranks. But Jake hasn't counted on the past to literally resist change, or the future to fly off in unexpectedly horrifying directions.

This is a lot of plot jostling for space – and I haven't even mentioned Sadie's nutcase estranged husband, the mysterious "Yellow Card Man" (a drunk always sprawled near the entrance to the rabbit hole), Jake's tangles with gamblers and gangsters, and a tantalising meta-apocalyptic alt-future in which JFK lives but the world goes to hell anyway. But rest assured: at nearly 750 pages, 11.22.63 has more than enough room to go around.

Considering how variable King's output is – the books I've read since his serious 1999 car accident range from compelling (Everything's Eventual) to underwhelming (Just After Sunset) to disappointing (Cell) to excruciating (Dreamcatcher) – 11.22.63 is something of a return to form. Stll, even the great man's biggest fans must acknowledge that there's always plenty of excisable fat in his longest books (The Stand, Insomnia, It, Under the Dome).

11.22.63 could easily lose 250 pages. I could have done without the recreated scenes involving the deranged, wife-abusing Oswald, which are unpleasantly voyeuristic without adding anything substantial. But even with a third too much larded prose, 11.22.63 delivers as an affecting, suspenseful page-turner.

Kevin Sweeney is an Irish Times journalist