In Hawaii, during World War II, U.S. Navy flyer Alec Brooke is unexpectedly reunited with his boyhood friend and former sweetheart, Nancy Fraser, who is now a Navy nurse serving in the Pacific theater. In the brief time they have to spend together, Nancy and Alex re-establish their romance and decide to marry when the war is over. A short time later, Alec's plane is hit by enemy fire, and he and his co-pilot, Lieutenant Joe Moore, are forced to make an emergency landing on the ocean. While stranded for days on the open sea without radio contact or fresh water, Alec tries to keep up his spirits by thinking about Nancy and his happy childhood in the small town of Westview, Iowa. Alec remembers the time when he dreamt of becoming a doctor, and when his eccentric, uncle Thad Vail, announced that he was leaving Westview to go on an expedition to find the fabled Pacific island of High Barbaree. When Alec comes out of his reverie, he and Joe consult their maps and realize, to their astonishment, that they are within one hundred miles of the area where High Barbaree is believed to be. While setting a course for the mythical island, Alec tells Joe about Thad's homecoming, which coincided with Alec's eleventh birthday: Soon after he returns to Westview, Thad decides to leave for the Gulf of Mexico, where he will be far away from Della Parkson, a spinster who wants to make a husband out of him. Alec and Nancy join Thad on his sailboat but the three get only as far as a nearby town, as Thad gets drunk and winds up in jail. Thad asks Nancy and Alec to telegram home for money to bail him out, but Alec decides to raise money for the bail himself by appearing in The Marlowe Bros. circus. While Alec performs in the circus, Thad's bail is paid by Alec's father, who enlists Thad's help in finding the missing children. Mr. Fraser eventually finds Alec and Nancy at the circus and brings them home. When the Frasers move to Montana, Alec and Nancy bid a tearful farewell and vow to reunite someday on High Barbaree. After concluding his story about his boyhood, Alec tells Joe about the time, many years later, when he dropped out of medical school to become an executive at an airplane manufacturing company: While working at the Case plant, Alec becomes engaged to Diana Case, his boss's daughter. Nancy, whom he has not seen in ten years, visits Westview, and Alec takes her to a big party at the Cases' home. Nancy is heartbroken when Diana's father announces the engagement of his daughter to Alec, and when Alec refuses to admit that he is only marrying Diana to further his career. Alec rejects Nancy's assertion that he would make a fine doctor until a tornado strikes Westview and forces him to use his medical training to save the lives of many of the injured townspeople. After realizing that medicine is his true calling, Alec breaks his engagement to Diana and plans to marry Nancy. Alec's decision comes too late, however, as Nancy has left Westview to marry a Navy man who had proposed to her earlier. Moments after Alec concludes his story, Joe succumbs to the effects of dehydration and dies. Alec, weakened by the heat, loses consciousness and dreams that he has arrived on High Barbaree. When he awakens, he finds himself in a military hospital attended by Nancy, who had decided not to marry the Navy man, and whose premonition about his whereabouts resulted in Alec's rescue. Nancy nurses Alec back to health, and they look forward to a happy future together.