Shortly after the end of World War II, Amy Atkins visits the London flat where she and her best friend, Tillie Grey, once lived. Housekeeper Mrs. Tubbs tells Amy that Tillie was about to leave for America to search for her serviceman husband, whom she married during the war, when she took ill and died. Out of concern for Tillie's twin children, Joyce and Johnny, Jr., Amy decides to finish Tillie's mission and, using a forged passport, sail to America posing as Tillie. Knowing only that Tillie's husband is named John Grey and that he lives in Rochester, Amy enlists the help of the Red Cross to locate him. Just before Amy's boat is due to dock in New York, John Grey, a Rochester, New York architect, receives a telegram informing him of his wife and children's imminent arrival. John, who is marrying Lois Evans, his boss's socialite daughter, that weekend, is stunned by the news, as he has no memory of Tillie or the twins. Later, John confesses to his best friend, Dr. Bob Davis, that he may have married Tillie while he was suffering from amnesia, which began when he hit his head on a lamppost during a London bombing raid. John reveals that for a six-week period, he lost his memory and was AWOL, but was eventually found by the military, which cured him of his amnesia and sent him home. With a lavish bachelor party scheduled for that night, John fails to meet Amy's boat, but begins a frantic, futile search for other Rochester men named John Grey. Amy, meanwhile, travels to Rochester and unwittingly checks into the hotel in which John lives. John is then humiliated when Amy, Johnny and Joyce are mistaken for a hired act and are jokingly presented by his friends at his bachelor party as his "wife and kids." Still posing as Tillie, Amy confronts John with his responsibilities, but John insists that he is not married. Terrified of Amy, who is camped out by the hotel elevator, waiting for him, John gets drunk with Bob and wanders into the street. After arguing with a policeman, John decides to "get amnesia" again and deliberately runs into a lamppost and knocks himself out. Later, Amy is informed by the police that her "husband" is at the police station. When Amy goes to pick up John, who is babbling about his amnesia, a reporter learns that she is a "war bride," and by the next morning, John's marriage is front-page news. With his engagement to Lois terminated and his job lost, John is resigned to becoming Johnny and Joyce's father and finds himself enjoying his new role. He also realizes that he is attracted to Amy, who fondly "recalls" their six-week romance. When John demands his conjugal rights, however, Amy insists that, as he has no memory of her, they must fall in love again. Frustrated, John seeks Bob's advice, but Bob, who is also attracted to Amy, suggests that Amy may not love the "new" John. Shortly afterward, Amy learns that the Red Cross has deduced her deception and is deporting her. The Red Cross also insists that, as she has no proof of the children's parentage, John cannot be held responsible for them. That same day, however, Amy receives two photographs from Mrs. Tubbs, one showing Tillie with John, and the other showing Tillie with Johnny and Joyce. Although the photographs assure the twins's future with John, Amy is still faced with deportation. After word of Amy's subterfuge spreads, John is reinstated by both Lois and her father and agrees to marry Lois the next day. That night, however, John concludes that he truly loves Amy and does not want Bob to pursue her. John pretends to have amnesia again and convinces Lois to call off their wedding with his odd pre-nuptial behavior. John then races off in the wedding car and crashes it into Amy's hotel. Later, in the hospital, John proposes to Amy, and Lois faints when she storms into his room and sees him snuggling with his children.