A terrible tragedy puts an end to a group of friends' vacation in Aruba. María (Victoria Ruffo) hears a gunshot and finds her friend Patricia (Montserrat Olivier) dead; in the confusion of the moment, she picks up the gun. María is thus found guilty of murder and is sentenced to life in jail. Her husband, Esteban (César Évora), an important businessman, does not believe her proclamations of innocence, and when he returns to Mexico he divorces her, buys the silence of all who were with them on the trip, and tells his young children that their mother died in an accident. He then erects a painting of another woman, whom he names Montserrat, above the fireplace

Twenty years later, María is freed from prison as a result of her good conduct and returns to Mexico City in search of vengeance. She wants to find Patricia's real killer and confront Esteban, whom she now hates for abandoning her, but what she wishes for most is to have her children, Héctor (Mauricio Aspe) and Estrella (Ana Layevska), back. The first thing that María does when she arrives is to confront everyone who was with her on the trip: Esteban; Servando (Lorenzo de Rodas), one of Esteban's business associates at the Empresas San Román; Demetrio (Guillermo García Cantú), Esteban's corporate lawyer; Daniela (Cecilia Gabriela), Demetrio's wife and the aunt of Esteban's fiancée, Ana Rosa (Martha Julia); Bruno (René Casados), another of Esteban's business associates; Fabiola (Sabine Moussier), Bruno's wife who is nonetheless in love with Esteban; and Alba (Jacqueline Andere) and Carmela (Margarita Isabel), Esteban's two aunts. Everyone is horrified to see María, and she puts fear and doubt into them when she tells them that she did not kill Patricia, and that the real murderer has lived among them for the past twenty years.

In the course of her investigation, María finds a portion of Patricia's diary and learns that her friend was not the good person whom she appeared to be: Patricia knew the secrets and weaknesses of everyone in their group and purposefully made María believe that Esteban had made sexual advances toward her. Furthermore, María learns that Patricia never loved her own son, Leonel (Eduardo Capetillo), and María resolves to prevent Leonel from learning this terrible truth.

María remarries Esteban so that she can win back her children's love; however, Héctor and Estrella are unaware that María is their real mother and loathe her, believing that María has come to usurp the rightful place of their mother, whom they have idealized. Plus, María must deal with the intrigues of her former friends, most notably Alba, who secretly harbors an incestuous love for her own nephew and hates all of the women who grow close to him, and Fabiola, who was once engaged to Esteban and resents María for winning his heart despite her low socioeconomic background.

María is also stunned to learn that Esteban has a third child, Ángel (Miguel Ángel Biaggio), whose mother Esteban refuses to name. Ángel is a frequently ill and insecure young man, and María accepts him immediately and treats him with love, and vice versa. Thanks to María's support, Ángel grows into a self-confident and optimistic man. Little by little, María wins her own children's love without revealing the true ties that unite them. She helps Estrella to mature and leave behind her life as a superficial and capricious youth, and helps her to understand that of her two suitors, Carlos (Sergio Mayer) and Greco (José Luis Reséndez), it is the latter who truly cares for her. Héctor is also immature and arrogant, and María helps him to accept responsibility when he falls in love with and impregnantes Vivian (Michelle Vieth), María's former cellmate.
However, María's biggest problem is Esteban. María finds herself at a crossroads when she realizes that she still loves her husband, and that he still loves her. Now, her heart hardened by twenty years of suffering, loneliness, and abandonment, María must find the strength to choose between vengeance and forgiveness.