Jan Bokak, an ignorant mine laborer engaged to Mary Berwick, is accused of the murder of her brother, Anton, on the night of his betrothal and accepts the blame to save her other brother, Alex. He escapes and makes his way to the steel mills owned by Cinder Pitt, where he becomes a leader among the workers and wins the admiration of Pitt, who has long tried to become his friend. Labor agitators try to wreck the mill, and Jan is seriously injured as he saves the life of Clare, Pitt's daughter; Pitt takes Jan to his home to recuperate, and Jan and Clare become engaged. In the mining town, Mary's mother reveals on her deathbed that she is the runaway wife of Pitt, the mill owner. When Mary finds her way to the Pitt home and sees Jan with Clare, she accuses him of the murder; at the mill, in dramatic fashion, Jan proves his innocence and forces a confession from Masarick. On the day of the wedding, Mary is hurt in an automobile accident, and Jan decides to marry her instead, incurring the wrath of the workers. Pitt learns of Mary's parentage and quells the mob, assuring them that Jan will get half interest in the mill.
—AFI