Sisters was produced and directed by Brian De Palma in 1973.  The plot focuses on a woman who witnesses from her apartment window a French model murdering a man. Desperate to convince the cops that the model is guilty of killing the man, she takes the homicide investigation into her own hands. 

Very similar to Psycho, the film Sisters opens with the concept of voyeurism. The scene begins with a TV game show called Peeping Tom and demonstrates a man watching a blind woman undress. DePlama seems to suggest in his opening scene that human beings are naturally voyeuristic. This is also seen in several other scenes, and it is performed by a variety of characters in the film. This is similar to Psycho’s theme of voyeurism because it also drives the plot forward in both films. In Psycho, Norman Bates watches Marion undress herself through a small peep hole, and his guilt from watching Marion leads him to kill her.  The woman who witnesses the French model murder a man also leads her own investigation, which allows the audience to discover the strange past of the model.

Another similarity between Psycho in Sisters is that the main killer is haunted by his or her past. Norman was haunted after he killed his own mother, and he often lost his identity to his mother’s. Similarly, the model often loses her own identity to her deceased Siamese twin sister who died during the procedure to separate them.

Along with the common traits in the main characters and the driving forces in the plot, the tone in each film is chilly, disturbing, downbeat, and menacing. Sisters is filmed with dark lighting, which seems to increase the menacing tone, especially when the model murders the man. It is sudden and abrupt, and it takes the audience by surprise and heightens the tension. DePlama seems to mirror the techniques in Psycho. When Norman murders Marion, her death is sudden, gruesome, and definitely creates tension for the viewer.