Steiger, a psychiatric patient, has developed an uncanny ability to disguise himself as women. He stalks and kills various women in this suspenseful game of cat-and-mouse.
Detective Segal is assigned to the case, and he begins uncovering clues. However, he also falls in love with one of the victims. It soon becomes clear that his new girlfriend may be the killer's next victim.
As the investigation deepens, Steiger's identity becomes more and more apparent. His behavior becomes increasingly bizarre, and he begins to exhibit signs of psychosis. The police are left wondering if he is truly insane or simply manipulating them for his own ends.
Meanwhile, Segal struggles to balance his personal life with his professional obligations. He is haunted by the thought of losing his girlfriend and the guilt of potentially putting her life at risk. As the case progresses, both he and Steiger become increasingly desperate to find the truth.
In the end, it is revealed that Steiger is not actually insane but rather a mastermind behind the killings. He had been experimenting on humans for years, using their bodies as a means to control others. Segal and his team finally succeed in capturing Steiger, but not before he manages to escape again.
The film ends with Segal reflecting on the events of the past few months. He realizes that he may have lost his girlfriend, but he also learned valuable lessons about the nature of evil and the power of justice.