Ikaw Lang ang Iibigin

This fictional drama teleseries follows the story of Bianca Agbayani (Francine Diaz) and Gabriel Villoria (Yogo Singh) who develop a special bond as young children in Zambales. They part ways when Bianca's family move to Manila. Gabriel (Gerald Anderson) and his family relocate to Manila more than a decade later when he pursues his studies.

In Manila, Gabriel juggles work, studies, earns his business degree, and becomes a triathlete. Bianca (Kim Chiu) obtains her accounting certification and becomes a promising young athlete like her mother. Bianca is scouted by TigerShark Energy Drink president, Carlos de la Vega (Jake Cuenca) to be their new endorser. A chance encounter at a triathlon event organized by TigerShark reunites Bianca and Gabriel and they fall in love. Although everyone within their respective families are happy about Gabriel and Bianca's rekindled relationship, their love faces threats by secrets of the past.

Bianca's mother, Maila Salcedo (Bing Loyzaga/Carla Humphries) was once an Olympic Triathlete, picked to represent her country at the ASEAN games. During a practice run, she is physically assaulted, resulting to permanent limb damage that ruins her career as a professional athlete. Her best friend Victoria Quintana (Ayen Munji-Laurel/Bangs Garcia) takes her spot in the Philippine team and garners the honor and celebrity status that comes with this national achievement. No one suspects fellow Philippine Team Triathlete Rigor Villoria (Daniel Fernando/Edgar Allan Guzman) as Maila's assailant, who commits the crime so that Victoria can take Maila's spot in the team. Rigor is a persistent suitor of Victoria who gets his way with Victoria with a one-night stand that results in a pregnancy.

Rigor is no match against another suitor, Roman de la Vega (Michael de Mesa/TJ Trinidad) a handsome and wealthy businessman. After a two-year courtship, six months of which Roman spends away in Europe for business commitments, Victoria and Roman get married. Shortly before their marriage, Roman learns he has a natural son from a former liaison, Clara Rivera, who dies in childbirth.

Away in Europe for the most part of her pregnancy, Roman does not detect anything. She delivers her son Gabriel just before Roman returns for their wedding and arranges to leave her son with Rigor. It was at this time when Roman's natural child surfaces and Victoria agreed to accept his natural son. Recognizing the opportunity to raise her son as a privileged and wealthy de la Vega, Victoria and Rigor swap Roman's son with their natural son.

Thus, the infant Gabriel assumes the identity of Roman's natural child, Carlos, and grows up in privilege and affluence. He is loved and overindulged by his stepmother, and a disappointment to his father who does not approve of his entitled ways.

Meanwhile, Rigor brings Roman's natural child Carlos to Zambales and gives him to his mother Lydia (Gina Pareño) to raise. Thus the infant Carlos assumes the identity of Rigor's natural son, Gabriel. In contrast to the other infant, Gabriel grows up in poverty, but is surrounded by a grandmother and an extended family who love, nurture and support him.

To cover her complicity in the infant swaps, Victoria frames Rigor as a drug dealer, sent to prison on a life sentence. For the next three decades, Victoria's life is perfect: she has wealth, social standing, a husband who loves her, and a stepson she dotes on. But Rigor is released from prison on a technicality and returns to Victoria for his rights to be close to her and their child. Her obvious anxieties over Rigor's sudden emergence into her life raises flags for Roman who suspects his wife of keeping secrets.

Rigor's return also strains the happy home Gabriel shares with his grandmother, Lola Ganda. Rigor openly dislikes Gabriel, who is disappointed over the cold reception he receives from his father. Rigor dislikes Bianca and purposely avoids rekindling a friendship with Maila, who is keen on catching up with her former teammate. Maila has no idea that the man who ended her career so abruptly is Rigor, the father of her daughter's suitor.

Roman's and Victoria's world becomes even smaller when Roman takes an interest in TigerShark. With no inkling that his natural son is just within his orbit, Roman decides to team up the popular sports couple as endorsers for Tiger Shark. Carlos is not happy with his father's interference in Tiger Sharks and he considers Gabriel an intrusion in his life particularly with his plans to court Bianca.

Still suspicious about his wife's past with Rigor, Roman investigates Victoria and learns of their previous relationship. Furious at her lies, he considers banishing her. Carlos is pained to see his mother's suffer, but he discovers his true paternity. The significance of this new information terrifies him. Concerned over losing his wealth and status, Carlos seeks Rigor's help to protect his mother's secret and eliminate Gabriel from their lives.

Victoria dies in a tragic accident. Fighting off Rigor's advances, she bounces off the rails of the hotel exit stairwell, falling several floors to her death. The suspicious death is blamed on Gabriel. Despite Carlos’ and Rigor's collusion implicating Gabriel with paid witnesses and manufactured evidence, Gabriel has a solid alibi to refute the charges and is cleared.

The worlds of the two brothers collide when Lola Lydia discovers Gabriel's true paternity and admits the truth to Roman, who orders DNA tests for Carlos and Gabriel. The DNA results confirm Gabriel is Roman's natural child and Carlos is not. Roman proceeds to formally adopt Gabriel, who now share the same legal status as Carlos. Carlos is not pleased with recent developments and schemes with Rigor to bring down Gabriel. Roman suspects Rigor has direct knowledge about Victoria's death, in Maila's accident, and with her kidnapping and subsequent fatal accident. Escalating conflicts between the brothers lead Roman to expel Carlos from the family and the company.

Roman grants Gabriel a management position in the company and Gabriel flourishes as a dela Vega. Carlos, on the other hand, gambles and loses his P100 Million inheritance and his wife Isabel suffers a mid term miscarriage. He blames all his misfortunes on Gabriel and vows to destroy him.

Without access to the de la Vega resources to pay his massive gambling debt, Carlos and Rigor strike a deal with the loan shark. They intercept an illegal courier carrying a large cache of smuggled diamonds belonging to a South African syndicate. Carlos discovers the illegal stash, steals some of the diamonds and plants the leftover cache in Gabriel's car to implicate him with the syndicate. As expected, the syndicate kidnaps Gabriel and try to kill him but he escapes with the help of Sylvia (Isay Alvarez-Seña), a neighbor who is suspiciously following him. Sylvia turns out to be his birth mother, Clara Rivera, who was secretly looking after him. A DNA test confirms the truth.

Roman hides Gabriel and pretends that his son is missing and presumed killed by the syndicate. Suspicious that Carlos’ sudden wealth has a connection with the syndicate, and using the resources of law enforcement assets, Gabriel obtains valuable intel exposing the loan shark and smuggling operations. In the meantime, a whistle blower admits to Roman about Carlos’ direct involvement in the recent company sabotage and plans for a corporate takeover. There is enough evidence to convict Carlos and Rigor to keep them in jail for a long time.

Bianca and Gabriel's joy over the birth of their son changes to fear when their child is kidnapped. This time, the two usual suspects have nothing to do with it because Carlos is held in custody and Rigor is fighting for his life from a gunshot wound. But there is one other person determined to hurt Bianca. Faking her pregnancy, Isabel had planned to take revenge by stealing Bianca's baby. Fortunately, her attempt to leave the country with Bianca's son is thwarted at the airport. Isabel is caught and placed in a mental facility.

At the prison hospital, Rigor dies but not before he calls his son on the phone to say goodbye and makes peace with his mother. He never apologized for his actions.

Accepting his mistakes towards Carlos when he was growing up, Roman visits Carlos in prison and asks for his forgiveness. He tells Carlos he will always be his father and promises to visit him everyday. Overwhelmed with his father's declaration of love, father figure, validation he craved all his life, Carlos asked his father to forgive him and wish that he is his real father than Rigor.

Gabriel and Bianca gather around the baptismal font during their son's christening. Surrounded by all their loved ones, they look forward to a bright future.

The drama's main theme music is "How Did You Know" performed by Daryl Ong.[1] A Tagalog cover version of the song entitled "Paano Mo Nalaman" is also performed by Maris Racal.

• List of programs broadcast by ABS-CBN
• List of drama series of ABS-CBN

• Ikaw Lang Ang Iibigin at TV Guide