Lt. Daniel Kaffee (Tom Cruise), a lawyer for the Judge Advocate General, must defend two marines accused of murdering a fellow soldier. Kaffee enlists the help of Jo Galloway (Demi Moore) and Sam Weinberg (Kevin Pollack), also lawyers for the JAG, in his investigation of the two men. As he begins to uncover the truth regarding the marine's death, Kaffee becomes convinced that the young soldier was not murdered but rather died during an ordered disciplinary action, one that has been outlawed within the military. Kaffee, an inexperienced trial lawyer, must argue against the charges filed and attempt to bring down the Colonel he believed ordered the beating: Nathan Jessup (Jack Nicholson).