I'm not normally a Stephen King fan, but this book surprised me. The premise was intriguing: an unassuming high school English teacher named Jake finds a portal to go back in time, but only to a particular time on a particular day in 1958. Every time he goes back, the past is a complete reset and all the changes made in the prior reality are undone. And every time he returns to 2011, only 2 minutes have passed, no matter how long has passed in the "Land of Ago". This time portal is located in the pantry of a local diner whose owner has convinced Jake that he needs to go back in time to stop the Kennedy assassination. The past is sensitive and maleable, but it doesn't want to be changed. And every flap of a butterfly's wings makes ripples.
Jake goes back in time for a reason that actually makes sense: he has nothing to lose. He is divorced from his alcoholic wife and has no family. During the five years he waits for Kennedy, he helps a variety of other people and changes a multitude of lives in unimaginable ways. He teaches high school in a small town, he falls in love with a small town librarian and becomes entangled in a very cute, enjoyable love story with only moderately awkward sex scenes.
As November 1963 approaches, the past bites back hard to prevent the changes Jake is already causing. The later half of the book has an unbelievable amount of plot that keeps you turning one page after another. There were certain effects that didn't make sense (how can natural disasters be at all caused by human actions) but King wrote those off as the universe ripping itself to pieces and was able to explain away the altered state of the future with a few pages. But every return it a reset, and it's all written away in less than a line.
The book ends on an up note after Jake discovers that the woman he loves is still alive in 2012, and has had an amazing, productive life since then. He tracks her down to dance with her one last time in a move that seems heartfelt in the confines of a story, but would seem stalker-ish, creepy, and a little gross in real life.
Overall, this was a well researched, addicting piece of sci-fi historical fiction (and much better than a slew of Stephen King's other, more recent works).