Charles Sadler is experiencing difficulty controlling his physical reactions, stabbing himself in the hand and killing his girlfriend. Dr. John Wilson has made tenure with his exploration of para-psychological cases, much to the chagrin of his younger colleague, Dr. Richard Austin, a confirmed skeptic. At a party, Dr. Wilson introduces Dr. Austin to a visiting paranormal case, Miss Helena Voyich, a one-legged woman who claims to be capable of mesmerism, a form of very powerful hypnosis dismissed by science in the late nineteenth century. She demonstrates on Richard's girlfriend, Audrey, causing her to do things she would never do of her own free will. Still unconvinced, and despite the insistence of Charles Sadler of the danger, Richard agrees to be a test subject so Wilson can submit a prize-worthy article. Helena interferes with his work, ignoring appointments with his student, Steve, and Chancellor Murdoch, and disrupting his relationship with his girlfriend in ways she is largely unaware, and having his maid wake him up at noon only for him to discover copious blood on his clothing...