Set in the years 2063–2064, the show focuses on the "Wildcards", members of the United States Marine Corps Space Aviator Cavalry, 58th Squadron. They are stationed on the space carrier USS Saratoga, and act as infantry and pilots of SA-43 Endo/Exo-Atmospheric Attack Jet fighters.

Harmon "Harm" Rabb Jr. is a former pilot turned lawyer working for the military's JAG (Judge Advocate General) division, the elite legal wing of officers that prosecutes and defends those accused of military-related crimes. He works closely with Lt. Col. Sarah Mackenzie, and together they do what needs to be done to find the truth.

Theorizing that one could time travel within his own lifetime, Dr. Sam Beckett stepped into the Quantum Leap accelerator and vanished... He woke to find himself trapped in the past, facing mirror images that were not his own and driven by an unknown force to change history for the better. His only guide on this journey is Al, an observer from his own time, who appears in the form of a hologram that only Sam can see and hear. And so Dr. Beckett finds himself leaping from life to life, striving to put right what once went wrong and hoping each time that his next leap will be the leap home.