Jake is introduced to a portal to a different time behind Al's Diner by the proprietor of the restaurant himself, Al Templeton. Al is (in)famous for his suspiciously cheap burgers and Jake finds out that Al can manage the low prices because the portal gives him access to September 9, 1958, where he can buy the burger meat at astonishingly low prices.
But Al is dying; quite quickly, in fact. He tells Jake about the mission he had set himself on; a mission to alter American history for the better. He planned to stop the assassination of John F. Kennedy, which took place on November 22, 1963 (11/22/63). But he had to live in the past for five years before he could reach the shooting and by that time he was diagnosed with cancer. So he passes on the mantle to Jake.
But the past is obdurate; it does not wish to change.
King covers the travelling-back-in-time dilemma with his characteristic use of mystery. But that's not the reason you will want to read this book. The real attraction of the book is in the huge amount of research that went into it. King paints a vivid picture of the past and the people he writes about - the historical ones, such as Lee Harvey Oswald [JFK's shooter] and Marina Oswald [his wife] - are real people and you can see their picture online, if you want.
The one thing that might put people off from the book is the fact that it is so very American, which may be hard to relate to. But then again, King has always been a very American writer. And it's not too hard to get used to his writing.
The book has its fair share of gruesomeness and evil, though not nearly as much as some of King's other works. Humans are nostalgic creatures and as Jake goes through his life in the past, moving from place to place, with cheap petrol and friendlier folks, you miss the good old days. Of course, there are certain places which are not very nice. Derry, Maine, for example. Those who have read King's “IT” will be pleasantly delighted by a couple of cameos.
All in all, a decent book. Not one of King's best works. The book is quiet; it draws you in after a few chapters and you will have no idea at which point you really got hooked - a book shaped after its writer. Nostalgic, a little intimidating, sometimes bitter, sometimes sweet; the book just dances through everything. Why not? When it is all said and done, “Dancing is life.”