Paulina Martínez is a gentle, caring and poor girl. She lives in a wooden house on a beach located in Cancún and works in a powder room at an expensive hotel to be able to pay for medicine her mother needs desperately. One day Paola Bracho, a rich and beautiful woman walks into Paulina's life. Upon meeting Paulina, Paola is shocked at the exact likeness between the two of them. Paola Bracho is a self-absorbed woman without scruples, heartless, cold, calculating and bored with her life. She is married to Carlos Daniel Bracho. Paola doesn't love her family and finds them boring, but she doesn't want to leave because the Bracho family is her source of financial security. Paola frequently travels under the pretense she has to visit doctors due to her supposed illnesses, but, in reality, she is spending time with her lovers.

Paola quickly begins to devise a plan by which she can escape with her new lover and Paulina can assume her identity within the Bracho family. Paulina doesn't want to accept Paola's plan, but then her mother's health worsens, which forces her to accept money from Paola in order to buy expensive medications. In exchange, Paola demands a test: she forces Paulina to take her place in a meeting with one of her lovers. Everything goes perfectly. Paulina wants to leave things at that, however Paola wants to continue with her scheme more than ever. She accuses Paulina of being a thief and blackmails her into taking part in this deception otherwise she will go to the jail. At the same time Paulina's mother dies and her boyfriend Osvaldo leaves her without a word of explanation. Thus, Paulina reluctantly agrees to impersonate.

Paola's husband Carlos Daniel Bracho is the overseer of the family's ceramic factory that has serious financial problems. He has been a widower for some years with two children that think Paola is their biological mother. He is blindly in love with his wife. His brother, Rodrigo, cannot convince him that his wife is cheating on him each time she says she has to travel to keep doctors appointments. 

Carlos Daniel also lives with his grandmother Piedad, his sister Estefanía and her husband Willy. Grandmother Piedad is a very strong person, who after her husband's death becomes an alcoholic. Estefanía and Willy cannot bear each other because Willy had an affair with Paola and Estefanía knows it. She didn't say anything to anybody because she wanted to avoid any unpleasantness between her husband and her brother.

When Paola finally prepares Paulina to take her place, Paulina comes to the Bracho house. At the beginning, her life in the house is very difficult. She finds it difficult playing the role of Paola. The situation that she finds there is also very trying and chaotic. The children are neglected, the grandmother is an alcoholic, and Estefanía and Willy are quarreling all the time. They all hate Paulina because they think she is Paola. She spends her days calming bad blood that Paola has caused. She immediately begins to show the Bracho family unconditional kindness and love. She helps grandmother Piedad overcome alcoholism and showers the neglected children with much needed motherly love and affection. She helps keep the factory from bankruptcy. She develops a special relationship with Carlitos who has become dependent on her. They are all amazed how "Paola" has changed, especially Carlos Daniel who doesn't know what to think because Paulina usually rejects him using the excuse she is sick. He starts to feel a renewed affection for his "wife", and Paulina begins to fall deeply in love with him. She knows he doesn't belong to her and she doesn't want to suffer when the time comes to leave the house. She is convinced that Carlos Daniel loves her because he thinks she is Paola.

Paulina's life will continue to be difficult. Gema, Carlos Daniel's jealous cousin, and Luciano, Paola's former lover, who knows that Paulina is impersonating Paola, will be against her. The height of Paulina's suffering comes when Paola decides to return and reclaim her former position within the Bracho family. Paulina has to leave the family that now she loves as her own. She'll be prosecuted for the crime she committed by impersonating Paola…