Sent on a mission to the South Pacific during World War II, Marine lieutenant Joseph Cable catches his first glance of the islands as his plane sails overhead. Meanwhile, on the beach below, Luther Billis, a fast-talking, wise-cracking sailor, tries to sell grass skirts to Bloody Mary, the bawdy trader who controls the concession. Billis is peeved that the island of Balai Ha'i, a treasure trove of beautiful women, souvenir trinkets and the legendary Boar's Tooth Ceremony, is off limits to enlisted men. Upon landing, Joe feels drawn to the nearby, fog-shrouded island while Bloody Mary leers at the young officer. At headquarters, Joe informs Capt. George Brackett, the head of the base, that he has been sent to establish a beachhead on Japanese territory along the coast in order to observe the movements of enemy vessels. To accomplish this, Joe hopes to enlist the aid of Emile de Becque, a mysterious French planter who possesses an intimate knowledge of the area. While Joe is outlining his plans, Emile is entertaining Navy nurse Nellie Forbush. The soulful, disillusioned Emile finds himself attracted to the bubbling, optimistic and younger Nellie. Finally overcoming his reticence, Emile declares his love and proposes, then confides that years earlier, he killed a bully in his hometown in France and was forced to flee to the islands. Aware of Nellie's relationship with Emile, the captain summons her to headquarters to question her about his politics. When they realize that she is unaware of his previous marriage or the children resulting from that union, Joe advises Nellie to forget her Frenchman. When the captain tries to enlist Emile in Joe's mission, Emile responds that he has too much to lose and that his experience with the bully has made him leery of becoming involved in causes. To ease Joe's disappointment, the captain suggests that he unwind, and Joe soon finds himself on a boat with Billis bound for Balai Ha'i. As the others watch the Boar's Tooth Ceremony, Bloody Mary introduces Joe to her young daughter Liat, and Joe immediately falls under the exotic girl's spell. Later, when the sound of the bell calls Joe back to his boat, he passionately kisses Liat and leaves in a daze. At Emile's estate, a party in Nellie's honor is ending, and after the guests depart, Emile finally introduces Nellie to his half-Polynesian children. Horrified that Emile was once married to a Polynesian, Nellie makes an excuse and hastily leaves. At this point, the film stops for a brief intermission. Some time later, Joe returns to Balai Ha'i to see Liat, and Bloody Mary mentions that a rich French planter has expressed an interest in marrying her daughter. As a gesture of love, Joe presents Liat with his grandfather's treasured pocket watch, but when he states that he will never be able to marry Liat, Bloody Mary snatches the watch from the girl's hands and returns it to Joe. As Thanksgiving approaches, Nellie, the star and choreographer of the base's Thanksgiving Follies, finds it hard to concentrate on the performance when her personal life is so painful. During a rehearsal, she breaks into tears and requests a transfer. The captain convinces her to reconsider, but when she receives flowers and an endearing note from Emile after the show, she runs from the stage and encounters Joe, who has just recovered from malaria. Recognizing that they are both suffering from lost loves, Joe confides that during his illness, all he could think about was Liat. Joe wonders why he finds himself unable to marry Liat, and Nellie suggests that they both need to return home where they belong. When Emile suddenly appears, Nellie informs him that her inbred bigotry will not allow her to marry him. Joe, in contrast, decides to defy convention and remain on the island with Liat. With nothing left to lose, Emile agrees to join Joe on his mission. After establishing a watch post in the hills, Joe and Emile begin to radio back information about the enemy position. Two weeks later, U.S. warplanes, guided by Joe and Emile's invaluable reports, have successfully driven back the Japanese. Concerned about Emile's safety, Nellie eagerly listens to his broadcasts, and when she learns that Joe has been killed, she realizes that she still loves Emile and prays for his safe return. For solace, Nellie goes to Emile's children, and as she sings one of their favorite French songs, Emile returns and they tenderly join hands.