Quantum Leap's Sam Beckett awakens to find himself in the body of the former captain of the starship Enterprise, Jonathan Archer. Due to crippling amnesia, he is unaware that a decade has passed since the Captain's mission to prevent the destruction of Earth has failed. With the help of Archer's companion T'Pol and his former crewmates, he manages to piece together Archer's past and put things right that once went wrong.

All kidding aside. Friggen fantastic episode.