Lt. Lisa Sherman, USN a Navy trauma nurse who once dated Al, appears in the Quantum Leap episode titled "A Leap For Lisa". The part of Lisa is played by actress Terry Farrell, who is perhaps best recognized to TV viewers as Lt. Dax on the Sci-Fi series Star Trek Deep Space Nine.
About Lisa[]
In the opening scene of "A Leap For Lisa" where Sam finds himself having leaped into his buddy and holographic guide Al, as a young Navy Ensign by the nickname of "Bingo" on June 25, 1957, he also finds himself on a beach with a beautiful naked woman emerging from the ocean kissing him, which he later learns is Lisa Sherman (guest star Terry Farrell), who was an old flame of Al's, a Lieutenant, and a nurse at the Naval Hospital on the base where they were stationed.
Al is currently under guard as a suspect in the rape & murder of Marci Riker, a superior officer's (CDR Dirk Riker, played by Charles Rocket) wife. He has an alibi though; on the night of the murder, he was with Lisa, an enlisted nurse serving on the naval base. Lisa is eager to prove Bingo's innocence but doing so could ruin their careers, as she is married, and Bingo is an officer. Sam assumes that he is there to prevent that, and discourages her from telling anyone about the alibi.
In the original timeline of sequences, A visibly distraught Lisa drives away from the guard shack where Al is being held, and gets killed in an automobile accident. But, after Sam's leap into a young "Bingo", and a change of events which lead initially dangerously towards Al's being tried in a court martial proceeding, (which pits his alibi against CDR Riker's) and Al's almost being wiped away from existence as "Ziggy", which became named "Alpha" in the brief timeline change, and the replacing of Al temporarily with one Edward St John V, a former Project Quantum Leap Lead programmer who produced the idea of the Leaping Chamber, (played by Roddy McDowall) as Sam's guide; Sam, with the help of Edward, is able to change the proceedings of Bingo's court martial, as well of the odds of Bingo getting convicted, by finding a key clue, a cigar left in Bingo's car which belonged to ol buddy, ENS Chip Ferguson (Jeff Corbett), who was, in the original timeline, with Mrs. Riker at the time of her death.
This also saves Al, who in the changed timeline, was convicted and sentenced to death in the gas chamber 3 years later in 1960; Al, unaware of his brief timeline discrepancy nor of his brief absence from existence after 1960, returns as Sam's guide in the restored 1999 timeline, and is able, with Sam's help is able to save both Lisa and Marci Riker's lives by going back to brief his younger self Bingo, on the situation, on how and why he leaped into the Leaping Chamber in 1999.
Al, who reveals himself to his younger self, or Ensign "Bingo" is able to get Bingo to leap back into himself at the base, replacing Sam at his quarters in 1957, where he was on the night of Marci Riker's accidental death. As a result, with Bingo not letting Chip, who visits him at his quarters, with a Marine MP guard in tow, out of his sight, Chip never meets up with Marci, the accident at the beach never takes place, the Marine sentry watching a then-under arrest, quarters confined Bingo disappears from the scene, and Lisa never gets caught up in the fateful auto accident, and meets Chip and Bingo, who never gets charged nor is at a Court Martial, there at Al's Quarters!