Paul Raden (Albert Dekker), the hopelessly insane son of Maxim Raden, hated owner of the Radentown mills, is in a straitjacket in a secret room in the family mansion while the body of his father is lowered into a grave. Twenty-five years earlier, the brutal father had hurled Paul against a wall when the young boy had tried to defend his mother, and with his brain injured forever, Paul's last memory before descending into the shadows of insanity, was his mother's agonized scream. At the graveside are Dr. Ben Saunders (Harry Carey), Paul's twin brother John (Albert Dekker) and John's wife Elaine (Frances Farmer). Pompey (Ernest Whitman), the family servant who has cared for and guarded Paul and kept the family secret for a quarter of a century, watches from afar. That night Dr. Saunders tells John that his twin, who he thought was dead, is alive as the father, refusing to commit him to an institution, had bribed the doctor to sign a false death certificate and bury another child's body as Paul. John and the doctor visit Radenhouse and find Pompey strangled and Paul gone. While they search frantically for him, he is enjoying his freedom and falling in love with the first girl he meets, Millie Pickens Susan Hayward), an unemployed mill worker. He wanders into a honky tonk filled with dancing jitterbugs, where pretty blonde Peggy Nolan (Jean Phillips) flirts with him; her body is found the next morning near the closed-down Raden Mills. Terrorized by the second murder and the thought that a homicidal maniac is on the loose, the town goes mad with fear and greed after Dr. Saunders tricks John into offering a $5,000 reward for the killer. Millie swipes her late father's revolver and persuades Paul, whose demented mind has forgotten the murders, to accompany her to Radenhouse, on her hunch that the murderer is hiding there.