Sin (also known as The Beloved and Restless) is a 1971 film written and directed by George P. Cosmatos and marked his directorial debut.

The film was produced by Curtwel Productions and stars Raquel Welch and Richard Johnson.

When her suspicious husband starts to show signs of jealousy, the adulterous couple plot to murder him.

The film was the second movie produced by Patrick Curtis, Raquel Welch's husband and manager.

Filming began on location in the Greek Cypriot village of Karmi, Cyprus on August 15, 1970.