Mac's "little sister" unexpectantly shows up at JAG headquarters, declaring that she's run away from her abusive stepfather. While she investigates whether Chloe has been abused, Mac has her hands full keeping her from turning the office upside down, then learns that her real father is still alive serving on a ship in the Navy. Despite the cost, Mac convinces the Admiral to allow the two to talk to each other via satellite video-conferencing.
After being diagnosed with night blindness, Lt. Cmdr. Harmon Rabb, an F-14 Tomcat fighter pilot, is forced to change careers. Cmdr. Rabb chooses to join the Navy's Judge Advocate General (JAG) Corps. There he both defends and sometimes prosecutes Navy and Marine Corps defendants. He is sometimes assisted by fellow lawyer, Lt. Sarah "Mac" MacKenzie, and his other fellow JAG staff.
Many of Rabb's cases require him to both keep up his F-14 qualifications and travel the world, in order to bring justice to the cases he is trying.
Rabb must also deal with the fact that his father, also a former Navy pilot, never returned home after being held prisoner after he was shot down in North Vietnam. Rabb believing his father is still alive continues the search he has pursued to find his father, since his teens.