In a heavy London fog in 1914 soldier Jack Ingleside bumps into an attractive woman. He begs her to have a drink with him, but she laughingly refuses him. To Jack's confusion, she seems to know him and to be amused that he doesn't know her. Before she leaves, Jack gets her phone number, and when he joins his brother Tom in a local pub, he tries to phone, but discovers he has written the number incorrectly. The next day, the two brothers, who are inseparable, travel together to visit their mother before they go off to war. To Jack's surprise, one of the guests at his mother's is the woman of the night before. Tom immediately recognizes her as Molly Prescott, a childhood neighbor and the only woman he has ever loved. Jack is smitten in his turn, and Molly returns his affection, although Jack's reputation as a ladies' man makes her nervous. Jack is serious, but when his mother tells him of Tom's feelings, Jack decides to step aside. He flirts with Sylvia, another guest, in front of Molly, and on the rebound, she agrees to wait for Tom. At the front, Jack successfully completes a difficult mission and is given a week's leave. By accident Jack runs into Molly in Calais, where she works as a driver. Once together again, they realize the depth of their feelings, and Molly asks Jack to tell Tom that she cannot marry him. Tom is devasted by the news. Giving up on life, he lets himself be shot by the enemy, but before he dies, he and Jack reconcile. After the war, Molly meets wounded war hero Jack at the train station, and together they begin their life without Tom