If you have seen Psycho, you have already seen most of what goes on in Sisters. It borrows the big secret from that film, it borrows the same focus on people's fear of their own sexuality, it borrows the same murder weapon, the same use of close calls to force the viewer to identify with the killer. Brian De Palma, who is known for borrowing liberally from other directors, certainly did his homework here.

We first meet Danielle (Margot Kidder) when she is a participant in a terrible game show where she pretends to be blind, walks into the men's locker room, and starts undressing. Philip (Lisle Wilson) is there, not knowing about the hidden camera. Two contestants have to decide how they think he will react. Since he is black, both of them think he will stand and watch her, but they are surprised. He's a gentleman, and he leaves. In return for his good sportsmanship when he finds out he was on TV, he gets tickets to a really awful club called "The African Room." He asks Danielle to go, and she grudgingly accepts. She is followed there by a mysterious man, who gets tossed out when Philip confronts him.

Back at her apartment (and you knew they would end up there), she complains of a headache, takes some pills, fools the mysterious man (who turns out to be her ex-husband and doctor), and hops in the sack with Phil. He hears her arguing with another woman named Dominique. The next morning, after he goes out for breakfast, he returns to find someone he thinks is Danielle on the couch, but she turns out to be Dominique, and she horribly murders him with the set of steak knives she won for playing on the game show. The murder, however, is witnessed by Grace Collier (Jennifer Salt), a columnist who hates cops, and she must try to convince the police that she isn't making the whole thing up.

De Palma does a neat trick with a split screen to enhance the tension in the scene when Grace and the police are making their way up to Danielle's apartment. Meanwhile, Danielle's ex is trying to clean up the murder scene. It's kind of cheesy when you think about it, but it works well at the time.

De Palma is an utterly unoriginal filmmaker who makes highly entertaining movies, the products of an expert craftsman. It's all about technique, and if you like the technique he's using, you'll like the film. He would have been perfect in the 1940s under the studio system, where his talents for blending into a genre would have served him well.