Fans of the best-selling book factory known as Stephen King are well aware that his vast body of work long ago transcended the horror/ghost story territory of "Carrie," "The Shining" and "It."

"1 1/2 2/6 3" still comes as a surprise. Epic in scope and length -- within hollering distance of 1,000 pages -- King's masterful new work deftly blends science fiction technique into the framework of historical fiction. Upon finishing the book, younger readers may know more about mid-20th century American life than some of their elders who lived through it.

The history is in the title, the last date before 9/1 1/0 1 when everyone in the country could tell you exactly what they were doing when they "heard the news." Our handsome young president, John Fitzgerald Kennedy, had been killed in Dallas, Texas, shot in the head when his motorcade was passing through city streets lined with cheering admirers. It was a day when everything changed.

The question King speculates on here is: What if you could change it back?

What if a person could go back in time and stop Lee Harvey Oswald from assassinating JFK?

The first few chapters of "1 1/2 2/6 3," in which King sets up his sci-fi scenario for time travel, are the densely explanatory price we pay for the rich world that awaits through his looking glass -- in this case a time "portal" from a diner's storeroom back to 1958.

A fairly intricate set of rules governs this portal, as far as its first user, the diner's owner, can tell: You always go back to exactly the same day -- Sept. 9, 1958 -- and it's always the same place (Lisbon Falls, Maine, where the book's hero teaches school, much as a young Stephen King did in a real town of the same name), and when the traveler returns through the portal, whether he has spent an hour, a month or five years "back in time," only two minutes will have passed in the present.

All these constraints exist to frame King's JFK dynamic: For instance, if the portal could take a person anywhere in time, why go after Oswald when you could stop Hitler, or Stalin, or even Pontius Pilate?

King says in his afterword, "I originally tried to write this book way back in 1972," but he gave it up because, not yet famous, he was teaching full time and the research needed would have been immense. More important, he writes, nine years after the assassination, "the wound was still too fresh." Time has done some healing and, also, in the 40 years since, much of that research legwork was done for him. He just needed to plow through it.

It was, let's say, time well spent. From this greater distance, King fills the pages with a vivid re-creation of an America that no longer exists -- a country where "Whites Only" signs still hang over drinking fountains and the only cars with seatbelts are on carnival rides.

Jake Epping, the hero, is hand-picked to go after Oswald by a casual friend of his, Al Templeton, the diner's owner. After a couple of trial runs, Jake reluctantly takes on the job.

As Al says encouragingly, it's a small price to pay if you can rewrite history, possibly preventing the Vietnam War, the assassinations of Robert Kennedy and Martin Luther King Jr. and all the turmoil that followed -- or, maybe not.

Once back in 1958, King takes Jake on a creepy sidetrip that gives the first hints that the past does not like to be tampered with. He plunks him down in Derry, the fictional setting for "It," King's book about a killer clown, a place whose downtown "looked only marginally more charming than a dead hooker in a church pew."

Here, Jake starts learning that changing even small events can have a "butterfly effect," starting an atmospheric disturbance that eventually causes a typhoon, or, more bluntly, the law of unintended consequences takes over.

Hence King's other big time travel rule: If you change the past, return to the present and don't like the result, you just go back to that same day in 1958 and everything automatically "resets," as though you had never been there before.

For the first 700 or so pages, the book is more accurately "1958-1963," as Jake moves in the shadow of Oswald through the South, eventually living right across the street and then in an apartment below him. His use of early electronic surveillance is fascinating; the way King fleshes out Oswald and his family life is even more so. We see a small man with a big ego and bigger aspirations, who abuses his Russian wife and is under the thumb of his Texas mother.

The streets are real, the people they meet are out of history books and Warren Commission reports, and, in a funny way, Jake fits in better in this time that he did in his own.

He gets a job teaching school, making more friends than he ever had and, unexpectedly, falling in love -- and that complicates his mission. Love and secrecy don't live well together. Jake can't reveal what he is up to, and he struggles with the idea of just letting history take its course. But it is Kennedy himself, as Jake sees him in action, that puts him back on course, first trying to find out if Oswald acted alone. Jake knows he could pull the trigger to stop one political nutcase, but preventing unknown conspirators from finding their target would be impossible.

King's answer on Oswald is that, after all his research, he is at least 98 percent sure that Oswald was no more than a fame junkie for whom the opportunity to kill a president landed in his lap -- no conspiracy. What is more interesting is how that belief plays out in his book, where love and time and the stubborn, angry past form their own conspiracy to keep Jake from changing the course of history.

Melinda Miller is The News' features editor.


1 1/2 2/6 3: A novel

By Stephen King


849 pages; $35.