A belligerent guy loses his girl-friend and joins the Navy to settle a feud with an officer; then he falls in love with the officer's sister.
Civilian iron worker Chesty O'Connor (James Cagney) starts a quarrel with Navy officer Biff Martin (Pat O'Brien) on the battleship Arizona. Chesty takes Gladys (Dorothy Tree) to a dance. Biff cuts in on Chesty, and they go out in the alley to fight. Gladys calls Chesty, and Biff knocks him out. Biff and Gladys win the dance contest. Chesty gets fired, and Gladys leaves Chesty for Biff. So Chesty joins the Navy and is sent to San Diego for 90 days training. Chesty and his pal Droopy Mullins (Frank McHugh) are assigned to the Arizona. Chesty loans Droopy $20 for his mother's false teeth. Biff tells Chesty that on ship they have no conflict. Droopy and Chesty see Dorothy (Gloria Stuart) greet her brother Biff. Chesty on liberty walks her home. He calls her, and she invites him to dinner. Dorothy makes Chesty apologize for making an advance. Chesty answers the door and finds Biff. They start fighting, but Dorothy stops it. Chesty leaves, and Dorothy asks Biff to apologize to Chesty.
Chesty gets a telegram from Dorothy, asking to see him that night. He asks for liberty, but Biff makes sure he doesn't get it by putting him on watch. Chesty buys a liberty card from a black sailor for $10 and puts on black to get on the liberty boat. He tells Dorothy he is quitting the Navy, but she changes his mind. She tells Chesty what to say to Biff and kisses him. To get back on the ship Chesty cries, "Man overboard." Biff testifies against Chesty, who is sentenced to two months restriction on ship and loss of $72 in pay. Chesty criticizes the Navy and is shunned by all except Droopy. When women come aboard, Dorothy kisses Chesty; but they argue. She tells him he can't whip the Navy. Ships do battle maneuvers. In the gun room Chesty stays to put out a fire and is burned. Now Chesty is a hero, as he receives the Navy Cross; but he gives it to Droopy and still wants a transfer.
Chesty boards a dirigible headed for a Navy celebration at Los Angeles. Biff hangs onto a trail rope and is lifted off the ground. Against orders Chesty goes down and ties Biff to himself so they can parachute to the ground. In the final scene Biff on crutches gives the bride Dorothy away to Chesty in a wheelchair. Once again Dorothy stops them from fighting. Chesty shows Biff his promotion to Boatswain above Biff's rank. Droopy's mother sings words that are tattooed on Droopy's chest.
The U. S. Navy cooperated in this story of Navy life in peace time. The aggressive attitudes of these two men toward each other reflects the masculine hostility that causes the military to exist.