You may never have heard of this neglected 1974 gem, but you've probably seen one of its many imitators. Olivia Hussey and Margot Kidder (also look for Andrea Martin of "SCTV" fame) star as two residents of a sorority house that is emptying out as Christmas approaches. The atmosphere is jolly and carefree, except for an ongoing series of menacing telephone calls, and, oh yes, we've just seen someone climb into the attic with apparent ill intent. Kidder does some scene-stealing as the bad girl, Hussey illustrates one of the downsides to having beautiful long '70s hair, and Keir Dullea does a nice turn as the creepy boyfriend. Director Robert Clark knows that the unseen is far scarier than what can be seen and he ratchets up the tension beautifully, making good use of ominous shadows, and putting in nice touches like replacing the sound of a distraught woman's scream with the piercing ring of yet another ominous phone call. This is a terrific, well-made little movie that is genuinely sleep-with-the-lights-on scary. Don't miss it. "--Ali Davis"