In a courtroom, Eddie Williams is on trial for the murder of Carl Hummel, his wife Helen's employer. Jean, Eddie's nine-year-old adopted son, is the only witness to the killing. When the district attorney attempts to have Jean testify, the boy does not want to betray Eddie, and Eddie stops his testimony by admitting to the killing. However, Dr. Castelli, Eddie's lawyer, reviews Eddie's background for the jury, explaining that he was a prominent singer in Broadway shows. In the past, Helen, Eddie's girl friend, brings him news that World War I has been declared. Eddie immediately decides to enlist, and just before he embarks for Europe, he and Helen marry. In the trenches, at Christmas, Eddie disobeys an order from his captain to shoot a German soldier who is attempting to cut a Christmas tree. Later, in a similar act of compassion, Eddie again spares the same German's life during a poison gas attack which leaves Eddie severely incapacitated. While Eddie attempts to recuperate in a hospital, peace is declared. Upon returning to America, Eddie is unable to resume his theatrical career due to the effects of the gas, which has impaired his lungs, and he becomes very despondent. Adding to his troubles is the news that his wife is being courted by her employer, Carl Hummel. Castelli continues his address to the jury by telling them that Helen has been posing as a single woman in order to get work so that she can look after Eddie. One night, Eddie discovers Hummel and Helen embracing and shoots Hummel. Eddie is unaware, however, that the embrace he witnessed was one of joy and gratitude resulting from their realization that Eddie is the American soldier who had saved his life during the war. Hummel had come to America to repay his debt by locating the soldier and arranging to have him treated by an important German doctor. Castelli also reveals that the district attorney was the former captain whom Eddie had disobeyed. The jury finds Eddie innocent and he, Helen and Jean are reunited.