Future Boy was the 13th episode of 3 of Quantum Leap, also the 44th overall series episode. Written by Tommy Thompson, the episode, which was directed bu Michael Switzer, aired for the first time on NBC-TV on March 13, 1991.
Sam leaps into Future Boy, the sidekick of 50's TV superhero Captain Galaxy. Al informs Sam that Moe Stein (played by Richard Herd), Captain Galaxy, is mentally unstable and that Sam is there to have Moe committed to prevent him from accidentally killing himself while trying to hop a train.
Sam doesn't think Moe is unstable and he feels that he is there for another purpose and that having Moe committed is not necessary. After talking to Moe, Sam learns that he is building a time machine and that Moe's theory of time travel is an incomplete version of Sam's own String Theory, which was the basis for Project Quantum Leap. Sam shares the rest of the theory.
Sam represents Moe in a mental competency hearing, but Moe loses and is sentenced to a mental hospital. Before he can be taken into custody and committed, Moe escapes and races back home to try his time machine, the Time-o-nometer. At first it looks as though Moe is going to Leap the same way Sam does, but the machine doesn't work.
Sam is successful, however, in patching up relations between Moe and his estranged daughter, who decides not to send her father to the hospital.
Before Sam leaps out, Captain Galaxy responds to one last reader letter (sent by none-other than a young Sam himself) and explains his theory of time travel that now includes what Sam shared earlier.