Really enjoyed this - slow start. But once Jake/George got going I enjoyed the book. Dîner owner Al Templeton finds a time portal that transports him to Lisbon Falls, Maine in 1958. Every time he goes through the portal - he returns two minutes later in the present - regardless of how long he was gone. After a number of trips for fun - Al decides he needs to stop Lee Harvey Oswald from assassinating JFK. He spends five years researching and studying Oswald’s movements - documenting his experiences. But - he is diagnosed with lung cancer in 1962 - causing him to return to 2011 and recruit Jake Epping to be the one to change history. 
Jake needs to see for himself that he can make changes - and when he is convinced - he goes back with the goal of stopping Oswald. 
Along the way