Quantum Leap had always been a fun show with a great hook, allowing Sam (Scott Bakula) to leap into the identity of different people week to week in an attempt to right some wrong. Aided by his faithful advisor Al (Dean Stockwell), every episode seemed rooted in Sam's unshakeable moral center. But that all changed when he found himself in the mind and body of Lee Harvey Oswald. The episode begins in 1957, six years before President Kennedys assassination, giving Sam literally years to try to stop the events of November 22, 1963. Yet as time progresses, Sam finds himself slipping deeper into the mindset of this man hellbent on making a name for himself in the annals of history. Much to Als horror, as the date in Dallas approaches, he discovers he is unable to break through to Sam, and it seems inevitable that events will unfold as history recorded them. But thats where the episode's hook comes in. After JFK is killed, a despondent Sam learns from Al that he did in fact correct the wrong that sent him into Oswald in the first place. As events were supposed to have unfolded, Jacqueline Kennedy was to have also died on that fateful day and Sams actions had saved her life. The episode is a great ride from start to finish that manages to play with the audiences expectations, resulting in arguably the best episode in Quantum Leaps run.