Sam finds himself leaping in and out of Lee Harvey Oswald, accused assassin of President John F. Kennedy. Beginning with Oswald's time in the Marine Corp in Japan in 1957, Sam leaps at random heading closer to the day of the assassination in 1963. Al assumes Sam is there to stop the assassination by uncovering a conspiracy involving Oswald. As Sam continues to leap further along Oswald's life his mind becomes tangled with Oswald's until he loses all control of his actions. Before Sam is lost completely Al discovers there is no conspiracy and must stop Sam/Oswald from killing JFK. In the end Sam and Oswald are separated and Sam's mission is completed. Al reports a change from the original history as Sam leaps out.