Dorothy, a victim of pre-natal influences who is reared by the hypnotist Balzamo to appear in public and continually display his powers, develops a second personality called "Becky," who hates the sweet Dorothy and does mischievous deeds in her name. When Balzamo tries to win her affection, Becky runs away. Meanwhile, Dr. Emerson, a specialist in nervous disorders, encourages Dr. John Arnold to use his hypnotic powers for good, relating that after a hypnotist induced his wife to leave him and take their child, his wife died deserted, and the child was never found. Although Dorothy acquires jobs, she loses them when the malicious Becky emerges. When Dorothy becomes a companion to Emerson's sister, Becky appears, and Emerson diagnoses the disorder as a case of dual personality. After Arnold, who loves Dorothy, is able to kill Becky, Balzamo arrives and attempts to revive his hold on Dorothy. Arnold wins the ensuing battle of wills and forces a confession from Balzamo that Dorothy is Dr. Emerson's daughter. His powers gone, Balzamo leaves, and now Dorothy accepts Arnold's love.