Celeste Janvier lives in an East Side tenement with her immigrant grandfather, Nicholas Marinoff, an old philosopher, socialist and humanitarian. Like Marinoff, Celeste is a kindhearted soul, whose friendly nature earns her the epithet, "the little sister of everybody." When several undesirable men court her, however, she is forced to turn them down. Meanwhile, Hugh Travers, Jr., whose father, a factory owner, has died suddenly, poses as a laborer in order to understand why his workers are threatening to strike. While working at the factory, he meets and falls in love with Celeste, and soon he secures a better job for her. When Celeste learns that anarchist Ivan Marask plans to kill Travers, she hurries to warn her employer and is astonished to learn that he is the poor laborer whom she loves. Marask comes to respect Travers, who agrees to improve conditions at the factory and finds happiness with Celeste.