Fascinating as opposed to wholly enjoyable, Bob Clark's Canadian sorority house slasher is largely gore-free, but bolsters the anaemia with a genuinely disturbing tone that draws on the creepy Old Dark House thrillers of old.
The fascinating part is how well it lives up to its reputation as "the film that inspired Halloween", with its holiday theme, dying teens and killer's POV the clearest connections. Viewed post-Scream it's often clunkily clichéd, but horror fans will delight in spotting precisely how much it has been ripped off ever since. Watch out also for a pre-Lois Lane Margot Kidder as one of the girls.
Having turned in a couple of half-decent zombie movies (Dead of Night  and Children Shouldn't Play With Dead Things ), Clark moved on to produce the intriguing Sherlock Holmes feature Murder by Decree (1978), before career freefall beckoned with Porkey's I and II (1981-83).