The Sunday Woman is a 1975 Italian film directed by Luigi Comencini. It is based on the novel of the same name by Fruttero and Lucentini.
The plot revolves around the murder of the enigmatic architect Mr. Garrone. The police commissioner Santamaria, played by Marcello Mastroianni, is assigned to investigate the case. As he delves deeper into the investigation, he discovers that Mr. Garrone had many enemies, including his own wife Anna Carla, played by Jacqueline Bisset.
Santamaria soon falls in love with Anna Carla and becomes obsessed with her, despite suspecting her of the murder. He struggles to balance his duty as a law enforcement officer with his desire for Anna Carla.
Meanwhile, Lello, played by Aldo Reggiani, is the lover of Massimo, a friend of Anna Carla who is also a homosexual. He conducts his own investigation into Mr. Garrone's murder, which leads him in a different direction than Santamaria's investigation.
As the two investigations progress, they begin to converge, leading to a shocking and unexpected conclusion.
The Sunday Woman is a thrilling murder mystery that explores the complexities of human relationships and the blurred lines between love and duty.