However, other books like Gerald Posner’s Case Closed swung me back again to the notion that Oswald had acted alone, in particular by exposing some of the rhetorical dishonesty on the pro-conspiracy side. (For one concrete example, compare the analysis of Oswald's "curtain rods" story by pro-conspiracy and pro-lone-gunman partisans.) I retained some niggling doubt about the ballistics until I saw a BBC documentary in 1993 that set my mind at rest on that point too. So basically I now accept that the Warren Commission, William Manchester, Norman Mailer and all those guys got it right.
Also a friend of mine interviewed Oswald's friends in Minsk as a researcher for this documentary, and came to the conclusion that Oswald was loopy enough to have done it alone (though would still have needed a lucky shot).
So now Stephen King gives his protagonist a way of going back in time from 2011 to 1958, with the mission of preventing the assassination, and therefore stopping the Vietnam War in its tracks and bringing about a better fifty years for American history. Our hero loves, fights, loses, wins, and then discovers that when he gets what he wants, it may not be what he wanted it to be. All the time travel cliches are there, but all done really well; I've often found Stephen King nostalgic for the 1950's/60s, both the good and bad parts of that time, and here he is able to indulge himself as a tourist of the past. The level of circumstantial and emotional detail is tremendous; one can almost smell Texas. (The time portal is located in Maine, which allows King to employ his love of his home state to great effect.)
With all that, I was a bit disappointed with the end of the book, where the real conspiracy is revealed and the story defaulted back into all the things I don't like about Stephen King's writing. But that was only for the last few dozen pages of a very long book. People who like King more than I do will like the book more than I did, and I liked it a lot.