Ann (Barbara Steele), a lonely recluse with an obsession for butterflies, is befriended by Alice. Ann, estranged from her own daughter, soon becomes close to Alice, and a disturbing mother-daughter relationship develops. But all is not what is seems and when Ann finds out that Alice has been tricking her, she descends into a madness that cannot be controlled. After committing a series of brutal and bizarre crimes, Ann tries to hide herself in her apartment, surrounded by her butterfly collection. Only someone has noticed Ann's strange behaviour, Julie, the girl who lives in the apartment next door. After discovering the dark secret hidden in the walls of the forbidden butterfly room, Julie is soon marked as the next victim. Bui can she survive or will she be smothered by this mother's love?