Brian de Palma has never really been given his due. Despite having directed a few of the quintessential gangster films (Scarface, Carlito’s Way) and at least one horror classic (Carrie), he’s no critical darling, usually derided as a second rate Hitchcock enthusiast. Whether or not that disqualifies him as a credible film-maker is debatable, but the influence of Hitchcock is strongly felt in 1973’s Sisters, his first properly mainstream film.

Sisters is on the one hand a horror film. Margot Kidder plays an actress living in Staten Island. She’s charming and spirited, but she also has a twin sister who is far less congenial- to the extent that she murders one of her twin’s boyfriends. Their neighbour, a journalist (Jennifer Salt), witnesses the killing, but when the police ignore her, she decides to uncover the truth- inevitably awful- herself.

On the other hand, Sisters, with its investigative reporter heroine, is a work of political commentary. De Palma’s films before this were effectively agit-prop, but here he weaves that style into a more conventional thriller narrative. By the end, the characters have wound up in a mad house, which is either just a mad house, or a symbol of America’s post-60s breakdown. Both readings work and neither diminishes the power of the other.

Sisters is a technical triumph, featuring some excellent use of split-screen and a moody Bernard Herrmann score, marking this as an extended homage to Hitchcock. It takes great skill to achieve that, but less in the way of an original vision, which is perhaps why De Palma remains a contested film-maker. On its own terms, though, Sisters is an effective little horror film, and that’s really all that matters.