When his wife realizes she loves her husband's best friend, the husband gets hurt and sacrifices himself on their railroad job.
Bill (Grant Withers) jumps off the train and eats at the counter where Marie (Joan Blondell) works. She reminds him they're getting married; but he is going to see his friend Jack and his wife Lily. Bill is thrown out of a house drunk, and Jack (Regis Toomey) takes him home. Bill helps Peg-leg (J. Farrell MacDonald) dig in the garden, and Lily (Mary Astor) plants sweet peas. Lily trims Bill's hair, and he plays. She sews a button for him and says he should marry. Bill likes Lily; she loves him, and they kiss. Lily doesn't know what to do about Jack and says only he is happy now; she doesn't want him to know. Bill says Jack should know. When Jack comes back, Bill leaves. Jack asks Lily what is wrong and suspects she is lying. He goes out and finds Bill at the counter. Marie tells Jack that Bill must have fought with Lily. Bill tells Jack he is not going back to his house. Jack calls Bill yellow and a liar. Bill says he kissed Lily and explains what happened. They fight on the moving train and don't see the signal. Jack is injured, and Bill says he was asleep from drink.
Tipsy Bill necks with Marie, and she suggests they get married. Ed (James Cagney) dances with Pearl. Bill rips the sweet-pea flowers off Marie's dress, and she runs out. In the rain Bill calls on Jack; but Lily says he won't see him. Bill goes in to find Jack blind. Jack hears Peg-leg call Bill's name. Jack tells Lily to go to her parents, saying he can't stand the pity. The rain causes a flood. Ed consoles Bill about Jack. Bix takes coffee to Jack and the guys. Bix and Ed say that Bill wants to take an engine on the bridge; but Kennedy won't give him permission. Jack sneaks out the back and stumbles to the engine and takes it out. Bill sees Jack and jumps on board. They argue, and Bill tells Jack to get off. Bill says that Lily is Jack's. They shake hands, and then Jack knocks Bill out and throws him off the train. The train causes the bridge to collapse, and both the bridge and the train are washed away by the surging river.
At the counter Bill stops for breakfast. Returning Lily comes in and smiles. She is planning to work on her house and invites Bill to come over. Bill goes back to work and seems happy.
In this romantic triangle the lover is honest with the husband; but they still fight with tragic results. It is difficult not to get upset when such powerful emotions are aroused. Finally the husband makes a heroic sacrifice so that his wife and his friend can be happy.