Mariana is a young, beautiful, true and intelligent girl, with a strong drive for self-improvement, but very few opportunities to get ahead. An orphan of both father and mother. She is left alone in the world when her godmother dies, which complicates her life more than she could have ever imagined. However, her destiny changes when she meets Alberto Salvatierra, the food industry magnate.

During a meeting, Don Alberto and his son Luis Alberto clash. The father-son relationship has been damaged by a past tragedy in which Matías, Luis Alberto's only brother, died. Don Alberto leaves the meeting with an uncontrolled heartbeat and has a heart attack. Mariana sees him and saves his life. When he recovers, he looks for the young woman and helps her by taking her to live in the Salvatierra mansion, where Daniela, Don Alberto's second wife, Luis Alberto and Santiago, his son from his first marriage, also live.

Mariana's arrival to the Salvatierra business world worries and alerts Soraya, shareholder and partner, Luis Alberto's lover, adopted daughter of Rafael Montenegro, now deceased, Don Alberto's friend and partner. Soraya is an ambitious and unscrupulous woman whose only driving force is power and money. Another member is Leon, the holding company's CFO. He moves in the shadows and manipulates Luis Alberto to oppose his father. During the last years, he has built several companies competing with the Salvatierra's in parallel, and he has done it with their own money. Not only ambition dominates Leon's actions, but also revenge, as he has been in love with Daniela since before she married Don Alberto. Therefore, he wants to destroy Alberto and become as powerful as he is, believing that this will make Daniela succumb to him. 

Mariana and Luis Alberto's relationship develops from their differences, she takes him to her world and he takes her to his. These complicities and desires end in a passionate and beautiful love. However, their enemies will do anything they can to separate them. In her quest to destroy Mariana, Soraya discovers a shocking secret: Mariana is Rafael's biological daughter, therefore, they are half-sisters, both heirs of Rafael Montenegro. Soraya won't reveal this secret to anyone and yet at the same time she is driven to destroy Mariana. First she lies to frame Luis Alberto for Rafael's death. This leads them to a separation and drags Luis Alberto back to his gambling addiction, on the other hand, Soraya slowly begins to give Mariana a poison, so as not to raise suspicions and thus get rid of her forever.

Upon discovering the truth, Luis Alberto and Mariana resume their relationship and begin the preparations for their wedding, while the poison is administered in parallel. Mariana starts feeling the effects, but it all happens gradually and can be attributed to the stress of the wedding. Finally, the wedding day arrives, Mariana has asked Don Alberto to be her best man, and while Luis Alberto and his mother are waiting, Mariana arrives on Don Alberto's arm, and to everyone's astonishment, she faints. In the hospital, Mariana struggles between life and death, but finally, after moments of distress, Mariana manages to survive. The wedding takes place, the honeymoon and everything seems blissful when Mariana becomes pregnant. However, her enemies continue to work from behind the scenes.

Don Alberto participates in a tennis tournament and Leon finds his big opportunity there. He adulterates the contents of the tournament drinks and Don Alberto drops dead in the middle of the court. After his death, everyone's ambitions are unleashed. Leon and Soraya believe that their time has come, especially with the birth of Mariana's son, who spirals into a baby blues. Luis Alberto, worried more and more about his wife's health, but also absent in order to keep the company afloat after his father's death, asks Daniela to take care of Mariana.

Mariana escapes from her home taking baby "Betito" with her and, confused in her mind, leaves the child in the arms of a street vendor. The kind-hearted woman waits in vain for Mariana's return and by nightfall ends up taking the child home, unaware that Mariana has fainted in the middle of the street. Luis Alberto finds Mariana and she provides him with the details of the woman to whom she left the baby. But a fierce fire broke out in the woman's neighborhood, she died, and the police found Betito's necklace among the debris, assuming his death. 

Everyone is convinced that Betito is dead, everyone except Mariana, who begins a tireless search. Eventually and in order to make the pain more bearable, they decide to adopt María Isabel. Despite loving her daughter, the search for Betito completely absorbs Mariana. This gradually separates her from her husband, who will once again seek an outlet for all his anguish in gambling.

Soraya becomes an obstacle for Leon's projects. He looks for a way to manage her and when he discovers that Mariana is Rafael's daughter, he threatens Soraya, but she decides to kill him. The scandal breaks out and Soraya is judged and sentenced to 25 years in prison.

18 years later, Mariana and Luis Alberto's marriage is in crisis. Mariana is the head of a foundation that searches for missing children and has a television show which also deals with searching for missing people. The hope of recovering Betito hides behind all this.

Unbeknownst to anyone, Soraya is freed for her good behavior. On her way out, Soraya prepares her revenge. She seduces billionaire Victor Millan, a widower who has a crippled daughter from an accident. Later, taking advantage of the contacts she made in prison, Soraya has Victor killed and keeps everything for herself.

Meanwhile, Mariana manages to find a clue about Betito and discovers that he has lived in the south side of the United States. Mariana approaches him and after numerous comings and goings, she confesses to him that she is his mother.  Luis Alberto, estranged from his wife, has found in Vivian someone with whom he can endure the anguished life he leads. She runs a poker table for millionaires as hostess and organizer. Soraya's revenge includes seducing Betito to make Mariana and Luis Alberto's life miserable when they find out what goes on.

The reconstruction of Luis Alberto and Mariana's love will suffer new obstacles, not only Soraya, but also Vivian and Luis Alberto's own addiction. Their mutual love will have to overcome the deepest sorrows and the most terrible tragedies, and it will make Mariana understand that the rich also cry.