The Sisters (1973)
Before director Brian De Palma started taking himself too seriously, he made a few effectively frightening films. His best by far remains Sisters (1973), his first stab at echoing Hitchcock, which succeeds because it mirrors the master's creepiness rather than flat-out mimics it, as too many future De Palma films did. A very young and alluring Margot Kidder stars as a woman with a creepy sibling past who may or may not be seriously disturbed, and who collides with Jennifer Salt (in her pre-Soap days) as an intrepid reporter who believes she has witnessed a murder (obvious shades of Rear Window). De Palma brings it in just this side of yucky gory, creating a disturging tone that's heightened by longtime Hitch collaborator Bernard Herrmann's marvelously eerie score. See this one late and in the dark for maximum frights.