The Mafu Cage (also released as My Sister, My Love, Deviation and Don't Ring the Doorbell)[2] is a 1978 American psychological horror film[3][4] 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, is an astronomer, and the other, is a dysfunctional eccentric who keeps and tortures a variety of monkeys and other primates.

Arthur worked with screenwriter Don Chastain to loosely adapt Eric Westphal's play Toi et Tes Nuages, which she had seen in Paris in 1975.

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.

Meanwhile, Ellen is romanced by David Eastman (James Olson), a coworker at the Griffith Observatory, but she is hesitant to allow him into her private life due to her and her sister's unusual circumstances.

Later that night, she paints her face red and dresses in tribal regalia to enact rituals studied by her father amongst African tribes; using an ornate wooden club, Cissy bludgeons David to death, and subsequently buries his corpse in the garden.

Arthur—who spent some time in a mental hospital as part of the research process—was able to shoot in the mansion rent-free, and she says she also managed to convince art galleries and museums to loan her artifacts for the film's sets.