In 1941, bugler and career soldier Private Robert E. Lee Prewitt transfers from Fort Shafter to a rifle company at Schofield Barracks on the island of Oahu. Because Prewitt was also a boxer, Captain Dana "Dynamite" Holmes wants him on his regimental team. Prewitt refuses because he stopped fighting after he blinded a friend. Holmes makes Prewitt's life miserable; and ultimately orders First Sergeant Milton Warden to prepare a court-martial. Warden successfully suggests doubling Prewitt's company punishment as an alternative. Prewitt is hazed by other non-commissioned officers and is supported only by his close friend, Private Angelo Maggio.
Prewitt and Maggio join a social club where Prewitt becomes attracted to Lorene. At the club, Maggio gets into an argument with stockade Sergeant Judson. Later, at a local bar, Judson provokes Maggio and the two nearly come to blows before Warden intervenes.
Warden, despite warning from another sergeant, risks prison after beginning an affair with Holmes' wife, Karen. Karen's marriage to Holmes is fraught with his unfaithfulness which was exacerbated after the stillbirth of a child and Karen's subsequent infertility. Karen encourages Warden to become an officer which would enable her to divorce Holmes and marry him.
Maggio is sentenced to the stockade after walking off guard duty and getting drunk. This results in harsh treatment at the hands of Judson. Prewitt discovers Lorene's name is really Alma and her goal is to make enough money at the club to return to the mainland and live a proper life. Prewitt tells her his career is in the military, and the two wonder whether they have a future together.
A sergeant named Galovitch, who is a member of Holmes' boxing team, picks a fight with Prewitt. The fight is reported to Holmes who observes it without intervening. Prewitt gets the best of Galovitch, and Holmes learns Galovitch started the fight, but Holmes issues no punishment. Higher-ranking officers observe Holmes' conduct and force his resignation in lieu of a court martial.
Maggio escapes the stockade after a brutal beating from Judson. His injuries are aggravated during his escape and he dies in Prewitt's arms. Prewitt seeks revenge against Judson and the two stab each other in a back alley. Judson dies from his wounds and Prewitt, severely injured, goes absent without leave and stays with Lorene. Warden covers for his absence.
The captain that replaces Holmes demotes Galovitch and affirms that boxing will not be used as a pathway to promotion.
Warden tells Karen about Prewitt. Karen tells Warden that Holmes' resignation is forcing them back stateside; but Warden divulges he is not interested in becoming an officer. Karen walks away with both realizing their relationship has ended.
The Japanese attack Pearl Harbor. Warden keeps his head in the chaos. That night, Prewitt attempts to rejoin his company but is killed when he refuses to halt. Warden identifies him as a good soldier, but a hardhead.
Karen and Lorene coincidentally stand next to each other on the ship that is taking them to the mainland. Karen throws her leis into the sea wondering if she will ever return to Hawaii. Lorene tells Karen she is not returning and that her "fiancé" died heroically during the Pearl Harbor attack and was awarded a silver star (none of which is true). She names Prewitt as the fiancé, and looks at his bugle mouthpiece which she is holding. Karen recognizes the name, but stays silent.
Burt Lancaster as First Sergeant Milton Warden
Montgomery Clift as Private Robert E. Lee "Prew" Prewitt
Deborah Kerr as Karen Holmes
Donna Reed as Alma Burke / Lorene
Frank Sinatra as Private Angelo Maggio
Philip Ober as Captain Dana "Dynamite" Holmes
Mickey Shaughnessy as Sergeant Leva
Harry Bellaver as Private First Class Mazzioli
Ernest Borgnine as Staff Sergeant James R. "Fatso" Judson
Jack Warden as Corporal Buckley
John Dennis as Sergeant Ike Galovitch
Merle Travis as Private Sal Anderson
Tim Ryan as Sergeant Pete Karelsen
Arthur Keegan as Treadwell
Barbara Morrison as Mrs. Kipfer
George Reeves as Sergeant Maylon Stark (uncredited)
Claude Akins as Sergeant "Baldy" Dhom (uncredited)
Alvin Sargent as Nair (uncredited)
Robert J. Wilke as Sergeant Henderson (uncredited)
Carleton Young as Colonel Ayres (uncredited)
Kristine Miller as Georgette (uncredited)
based on the 1951 novel of the same name by James Jones.