Making its NBC debut with a two-hour TV movie on March 26, 1989, the weekly, 60-minute science fiction series Quantum Leap starred Scott Bakula as physicist Sam Beckett, who, as the result of a botched experiment, was sent hopscotching through time and space, "leaping" into the bodies of strangers. During the series' first season, Sam was confined to traveling within his own lifespan, which began with his birth in 1953; later on, however, he made an occasional jaunt into the 1940s. Though he was able to change the lives of the people whose bodies he had briefly "inherited," he was not permitted to alter the course of history. In the tradition of Here Comes Mr. Jordan and other soul-transmigration stories, Sam always looked like "himself" to the series' viewers, but those around him saw him as the person he was supposed to be. (This set-up provided some amusing moments whenever Sam leapt into the form of a woman -- and especially in one episode, in which he became a chimpanzee!) Throughout his cosmic perambulations and permutations, Sam was observed and advised by Admiral Al Calavicci (Dean Stockwell), who was seen as a holographic projection, and who kept in contact with "Ziggy," the computer controlling Sam's leaps, by means of a pocket-sized electronic device. Except in special cases, Al could be seen only by Sam. After five seasons on the air, Quantum Leap concluded on August 15, 1993, with a somewhat existentialist finale which brought things full circle -- and which, to many savvy viewers, invoked memories of the similar finale to the cult series The Prisoner.
by Hal Erickson synopsis