The Mafu Cage (also released as My Sister, My Love, Deviation and Don't Ring the Doorbell) is a 1978 American psychological horror film directed by Karen Arthur, and starring Carol Kane and Lee Grant. Its plot follows two sisters, both the daughters of a late anthropologist, residing in a dilapidated Los Angeles mansion: one, an astronomer, and the other, a dysfunctional eccentric who keeps and tortures a variety of monkeys and other primates.

Plot

Ellen Carpenter (Lee Grant) is a successful but emotionally repressed astronomer in Los Angeles who resides with her sister, Cissy (Carol Kane) in a dilapidating house in the Hollywood Hills; the sisters inherited the home from their late father, a successful anthropologist who worked extensively in Africa. Cissy is mentally imbalanced, childlike, and unable to carry on a functional life on her own, spending most of her time caring for her pet monkeys—which she refers to as "mafus"—which she keeps in a large cage in the living room. None of the animals last long in Cissy's possession, however, due to her violent outbursts, during which she kills them.