Steel separates 1873 Pittsburgh into rich and poor, master and worker, powerful and powerless. On one side is Paul Scott, the progressive son of a steel mill owner. On the other is Mary Rafferty, daughter of an embittered laborer who was crippled in a mill accident. When Mary takes a post as a housemaid at the Scott mansion, she and Paul fall desperately in love. But a bloody strike may tear the city - and the lovers apart.