Tanya's Island (1980)

Tanya (Vanity) and her lover, Lobo (Richard Sargent), escape to the solitude and tranquility of a deserted tropical island. Upon arrival Tanya begins to explore her new found paradise. Each day she goes deeper into the jungle. During one trip she discovers a gorilla-like creature that, after many encounters, she befriends. Named "Blue" for the unique color of his eyes, Tanya learns to communicate with the beast. Jealous of Tanya's attention to Blue, a vicious rivalry develops between Lobo and the creature. Lobo, now taking on animal characteristics, takes Tanya prisoner and begins a brutal campaign to kill Blue. The beast, who has observed Tanya and Lobo together at play, at work and during lovemaking, now begins to develop human traits and needs. Terrified of both, Tanya is now caught in a fierce battle between man and beast for total possession of a beautiful woman.