Repressed astronomer Ellen Carpenter (Lee Grant) had a grind keeping up her collapsing Hollywood home and caring for her mentally unstable sister Cissy (Carol Kane), whose twin obsessions were her pet primates...and her sibling. Ellen's tentative relationship with colleague David Eastman (James Olson) sufficed to send Cissy over the edge--and both will feel her wrath in a shocking manner. Twisted tale of erotic tension and psychological terror also stars Will Geer. AKA: "The Cage," "Don't Ring the Doorbell," "My Sister, My Love," "Deviation." 96 min. Widescreen; Soundtrack: English.