Vivir un poco (1985)

Andrea is a very-well-to-do suburban housewife who in 1965 goes on a leisure trip to Argentina with some friends and relatives, including her husband, Gregorio, and her sisters-in-law, Aura and Rosa. During the trip, Martha, the wife of one of their friends is brutally killed and Andrea is sent to jail on account of the murder. 20 years later she is pardoned and returns to her country under an assumed identity to solve several mysteries: Who killed Martha? Why? Who is the mother of her husband's youngest son, who was born after her incarceration? To do this, and to get close to her children who believe her dead, Andrea must take desperate measures that might include a hasty marriage and even, start thinking like the killer did. Intrigue ensues soon after her return, for there seem to be more than one person who'd gladly see her dead...