A hole in time in the storage room of a Maine diner allows passage to a specific instant in 1958, and after a couple of experimental visits the protagonist embarks on a longer trip in order to undo several tragedies culminating, as the title implies, in preventing the assassination of President Kennedy.
I bought this at my favorite local bookstore and carried it with me into a restaurant I like two doors away, and when the waiter, who said he was thinking of getting the book himself, asked if I’d started reading it yet, I told him no, I’d picked it up only because I’d seen some dangerous-looking characters in the vicinity and wanted something heavy to use as a weapon. Less than a week later I informed a friend that I’d almost finished reading it, having only about 350 pages to go.
In short, this book isn’t.
But it keeps moving and never feels long. It takes a good story-teller to turn out an almost-850-page novel that never drags. I’ve read 200-page books that seemed vastly longer.
The hero is a divorced high school English teacher who's 35 at the start of the story. He tries a couple of tentative trips back to explore the possibilities before undertaking the main project. That one requires a commitment of several years, during which he travels, does a variety of things, and meets many interesting people. One of them is a woman who comes to mean a great deal to him, though he's afraid to tell her what he's really up to and isn't sure what he's going to do when he achieves his goal.
Even those of us old enough to remember the world circa 1960 might not recall some of the interesting details King brings out, such as (to take just one example) how much more primitive the practice of medicine was back then.
The book does have some flaws, including foreshadowing of the had-I-but-known variety that gets quickly annoying, but on the whole it’s very good. If you associate the name Stephen King with horror, note that there’s not a great deal of horror here, though there is some suspense and violence.