Sorority house is terrorized by obscene phone caller. Then people start disappearing. Early slasher film is an influential slice of horror which actually predates Halloween by 4 years. Doesn’t seem particularly innovative today because of the hundreds of horror films that came after it. However this film does have some dramatically menacing scenes. Exploitative in the way most slasher films are, but it is particularly notable for the way it treats the murders with more gravity. A good horror film, just not a great one.