Dr. Sam Beckett, desperate to prove his time travel theory before his top secret Project Quantum Leap (PQL) runs out of funds, leaps before the kinks are worked out of the machine. He ends up leaping into Tom Stratton (Layne Beamer), a pilot of the experimental Bell X-2 aircraft, trying to act as Tom while dealing with his own "Swiss cheese" memory. Sam corrects a X-2 incident that killed Tom, then helps Tom's pregnant wife, Peggy (Jennifer Runyon), from having to lose the baby. Ziggy, the super computer Sam designed for PQL, believes that fulfilling these tasks will allow Sam to leap home. Instead, Sam leaps into minor league baseball player Tim Fox (Ken Martin) in Texas at the end of the 1968 season, in the middle of a game, where he must make the winning play in order to leap further.

Notes:

• 1) Sam, starting a tradition seen in nearly every episode (exceptions noted throughout these synopses), utters the phrase "Oh, boy!" when he first realizes that he has leapt into a new situation.
• 2) For the first of only two times in the series (with season 4's "The Leap Back"), Ziggy is able to connect with Sam to try, unsuccessfully, to bring him home.
• 3) Despite his "Swiss cheese" memory, Sam surprises himself by knowing the exact medical procedure to save the baby, later learning that medicine is just one of his six doctorates and that Time "called him the next Einstein".
• 4) Originally shown as a feature-length pilot TV movie, which was later cut into two separate episodes for syndication.

As Gerald Bryant (John Tayloe), a lecherous old professor at a private university, Sam's mission is to stop young student Jamie Lee (Leslie Sachs) from ruining her life by entering into an ill-advised marriage with Sam's host, but along the way, Sam tries to change his own history by reuniting student Donna Eleese (Teri Hatcher), who will be a fellow PhD quantum physicist when she leaves him at the altar when they are 30, with her father before he ships out to Vietnam.

Sam leaps into New York City private investigator Nick Allen (Tony Heller), who looks like Humphrey Bogart and is looking for the murderer of his partner, Phil Grimsley, in a world akin to a Bogart film. The femme fatale of the piece is his partner's wife, Allison (Claudia Christian). Sam is aided in his efforts by Seymour (Willie Garson), the newsstand boy in his host's office building, which is managed by Lionel (Paul Linke). Sam remembers having read a pulp detective novel about the case, which Ziggy tracks down in order to help Sam out. The book reveals that Sam's host was murdered at LaGuardia Airport, and Al learns that Allison and Seymour disappeared, all in the next 24 hours. At LaGuardia, when an adolescent Woody Allen mistakes Sam for Bogart, Sam spots a delusional Lionel – who killed Phil, believing Allison wants to run off with him. Sam stops Lionel from killing the trio, but does not leap until he inspires Seymour to become a pulp novelist.