On his way to France to fight in World War II, Colonel Roy Cronin stops his cab on London's Waterloo Bridge and reflects on the past: It is 1914 and air raid sirens screech as a group of young girls hurry past, seeking shelter. One drops her purse and Roy helps its owner, Myra Lester, a beautiful ballet dancer, to retrieve it. They seek shelter together and a whirlwind wartime courtship follows, resulting in Roy asking Myra to marry him. Before the ceremony can be performed, however, Roy is called to the front and Myra is fired for her impetuousness by Madame Olga Kirowa, the troupe's tyranical ballet mistress. When Myra's friend Kitty sticks up for her, Madame Kirowa also fires her. Unable to find work in another ballet or show, the two dancers soon find themselves broke and hungry. One afternoon, Myra is supposed to meet Roy's aristocratic mother for the first time. While waiting, Myra sees a notice about Roy's death in the newspaper and faints. When Lady Margaret arrives, Myra cannot tell her the terrible news, and her erratic behavior shocks and angers Roy's mother, who leaves in disgust. Myra then falls ill and lies close to death from grief. To earn money to cover her friend's medical expenses, Kitty drifts into street walking. When Myra recovers, she is touched by her friend's sacrifice, and with no desire to live, she, too, becomes a prostitute. One year later, Roy returns to London, and the first sight that he sees upon getting off the train is Myra, who has come to pick up soldiers. He believes that she has come to meet him, and knowing nothing of her life in the past year, takes her home to his family estate in Scotland. Although Myra tries to convince herself that they can be happy, she soon realizes that her past will ruin Roy's life and, after confessing all to his mother, she runs away. Roy follows, despite Kitty's revelations about Myra, but she eludes him and kills herself by throwing herself in front of an onrushing truck on Waterloo Bridge. Clutching the good luck charm that he had once given Myra, Roy leaves for the front.