In the first section Gunnery Sergeant Hartman (R. Lee Ermey), a senior drill instructor in the Marine Corps, trains and indoctrinates a group of new recruits to Parris Island. In the opening scene he immediately singles out Leonard Lawrence (Vincent D'Onofrio) as a misfit. Nicknaming him Gomer Pyle, Hartman continues to physically and psychologically torment Pyle, making an example of him as a lesson to the others. Eventually this treatment begins to take its toll on Pyle and on the evening of their graduation and assignments, Pyle kills Hartman and commits suicide in front of Joker who was assigned to Firewatch duty.

The second part of the film takes place in Saigon, Vietnam in January 1968. "Joker" is Marine Combat Correspondent with the military newspaper Stars and Stripes. He has been assigned to a Marine public affairs unit with his new partner "Rafterman" (Kevyn Major Howard), a combat photographer. Joker's base is attacked during the Tet Offensive and Joker fights his first battle against the North Vietnamese Army. After the battle Joker is ordered to Phu Bai to cover the combat taking place in this region. He links up with "Cowboy" (Arliss Howard), his friend from boot camp, who is second in command of the Lusthog Squad and accompanies the squad during the Battle of Hue. During a patrol of the Perfume River the Lusthog Squad becomes pinned down by sniper fire. Several members of the squad are killed, including "Cowboy" before the squad is able to find and kill the sniper.