A city is rocked by a growing number of cases in which beautiful young women have disfiguerd themselves, seemingly for no reason, and with no memory of doing so.
Detective Dave Kennedy (Joe Patridge) and his psychologist friend Philip (Guy Prescott) attend Desmond's hypnotist show with Dave's girlfriend Marcia (Marcia Henderson) and Dodie (Merry Anders). During the show, Dodie is called on stage by Desmond and hypnotized. Later that evening, she washes her face with acid.
Marcia, suspecting Desmond, attends the show the next night and is called on stage to be hypnotized, but resists. She tells Dave and Philip that Desmond ordered her to return to his dressing room later that evening. She does so, pretending to by entranced, only to be hypnotized for real by Desmond's strobe-light "Hypnotic Eye."
Desmond takes the hypnotized Marcia out for dinner and dancing before returning to her apartment, where Desmond's assistant Justine (Allison Hayes) orders Marcia to step into a scalding hot shower. Philip and Dave interrupt just in time.
Dave interviews all of the mutilated women and all of them report that they have never been hypnotized or seen Desmond- even Dodie. Convinced that Desmond is behind everything, Dave and Philip head to the next show, where Marcia is in the audience.
When the heroes try to arrest Desmond and rescue an entrance Marcia from Justine, they discover that Justine is the real force behind the crimes; Desmond has been making other women "less beautiful" than his lover, who wears a lifelike mask to hide her horribly-scarred face.