Shivers (1975)

In a luxurious apartment complex, Dr. Emil Hobbes violently ends his life and a young woman’s, revealing a grotesque experiment. Dr. Roger St. Luc discovers Hobbes' work on a parasitic organism designed to merge with human organs, stimulating uncontrollable primal desires. As the parasite spreads among the residents, they transform into hypersexual, aggressive beings. Amidst the chaos, St. Luc races to contain the outbreak within the confines of the building.