Navy lawyers of the Judge Advocate General's office (JAG) investigate murders, espionage, treason, and other military crimes. Lieutenant Commander Harmon "Harm" Rabb Jr. is the son of a decorated Navy pilot who is still M.I.A. in Vietnam. Harm was a Navy flyer himself until a devastating plane crash. He took up law and joined JAG. Marine Major Sarah "Mac" MacKenzie is a JAG lawyer who faces the challenges of her missions while also dealing with personnel who respond to her gender instead of her uniform. Navy Lieutenant Bud Roberts is Rabb and MacKenzies's aide who attends law school by night and often surprises his superiors with his knowledge. Admiral Chegwidden is their no-nonsense boss, a former Navy Seal. Last season, Harm quit the courtroom to become a F-14 fighter. This season he returns to find that Mac has been promoted to colonel, outranking Harm.