Based on the stage melodrama by John Chancellor, King of the Damned takes place on a brutal prison colony that makes Devil's Island look like Disneyland. Cruel governor Courvin believes in strict discipline, and isn't above breaking a few backs to get what he wants. Finally the convicts, led by Number 83 (Conrad Veidt), overpower the guards and assume control of the island. Rather than escape, however, Number 83 establishes a communal farming system, with everyone working together for the common good. He also falls in love with Anna (Helen Vinson), the slain governor's daughter. Captured by the navy, Number 83 is brought back to his own country, where he successfully pleads for humane treatment and the right to self-determination for his fellow inmates.