Burt Lancaster is a retired American professor who lives alone in an ornate Roman house. Into this well-ordered life comes a decadent matriarch, her nubile teenage daughter, her husband, and her sometime-lover. They rent the upstairs apartment, and thus begins a series of intrigues, sexual involvements which provoke flashbacks of the professor's life that reveal his relationships with his wife, Cardinale, and his mother, Sanda. The Professor exists between these two realities and rushes from one to the other with torment and hesitation.