Dr. Kannadasan MBBS [Vivek] is a fertility doctor who runs a Chennai fertility clinic with the help of his assistant R.S. Shivaji Kaamu. He promises high-quality sperm for his patients but is frustrated by his inability to find a healthy donor. Through a contact at the Employment Exchange Department, he reviews applications filed under the sports category and identifies Harish Kalyan as Prabhu Govind, a cheerful young footballer who dreams of a government post to support his mother Vanathi Anupama Kumar and his grandmother, who run a beauty spa.
One day, while making a delivery at a mall at his mother's request, Prabhu meets Nidhi Mandhanna Tanya Hope, an employee and divorcee, and is instantly smitten. He notices Kannadasan tailing him and is asked to donate sperm, which Prabhu declines at first. Undeterred, Kannadasan follows Prabhu everywhere, while Prabhu regularly visits Nidhi at the mall and the pair grow closer.
After witnessing his football coach lament the inability to have a child with his late wife, Prabhu has a change of heart and agrees to donate, with Kannadasan paying him for each donation. Prabhu spends the money freely, concealing the donations from his family. Everything changes when he discovers Kannadasan has sabotaged his attempts to gain stable employment to keep his clinic afloat. He ends the association and decides to marry Nidhi. Yet Kannadasan, seeking to repair the damage, helps Prabhu secure his dream job and mends the rift with Nidhi's family, leading to their marriage. Prabhu, now reconciled with Kannadasan, makes one final donation, and Kannadasan secretly uses Prabhu's sperm to conceive a child for a state minister, earning a substantial settlement.
Three years pass and Nidhi yearns for a child, but they remain unable to conceive. Kannadasan reveals that Nidhi is infertile, leaving Prabhu devastated. Despite Kannadasan's suggestion of surrogacy, the couple chooses to adopt a child and welcomes Kavya, a three-year-old girl whose parents died in a car accident. Later, Prabhu discovers Kavya is actually his biological child, conceived through one of his donations, which shocks him. He confronts Kannadasan, who confirms the truth and urges him to love Kavya and keep her origins secret from the family.
The family grows closer to Kavya, while still unaware of the full backstory. The Income Tax Department arrests Prabhu on charges of handling black money, and Kannadasan helps him. With no other record, Kannadasan reveals the truth to the police, and the minister's influence helps them escape prosecution. Nidhi is disgusted by the disclosure and leaves Prabhu. Later, Kannadasan hosts a function at an orphanage with Prabhu, Nidhi, Kavya and the other families affected by Prabhu's donations. He explains that, despite the secrecy, Prabhu brought happiness to numerous families and that 49 children were conceived through his donations. With a renewed understanding, Nidhi reconciles with Prabhu, and the group—Prabhu, Nidhi, Kavya, Kannadasan and the families—celebrates the bonds forged through these controversial acts.
