Chandrasekar, popularly known as Sekar, along with his close friend Sundaram, forms a deep bond during their college days in Madurai. They share a friendship that is further strengthened through their common struggles and aspirations. Meanwhile, Sathyabama "Bama", who is also a college mate, belongs to a family that owns a bus company, with her father Ramalingam and mother Alamelu—a strict woman who exerts considerable influence over Bama’s behavior. Alamelu’s controlling nature has a significant impact on Bama, shaping her into a somewhat dominant personality.
As their lives progress, Sekar and Bama fall deeply in love despite the objections of Alamelu. Her disapproval initially causes Sekar to leave Bama, but after recognizing Sekar's intelligence and resourcefulness, Alamelu eventually agrees to their marriage. Following the wedding, Sekar moves into Bama’s household, where he is appointed as the manager of the bus company. However, he struggles with feeling powerless, as he lacks the authority to make major decisions or handle the company’s financial matters, which deeply frustrates him over time.
A year into their marriage, Bama gives birth to twin daughters, Lalitha "Lalli" and Padmini "Pappi". Despite the joy of welcoming her children, Sekar continues to face challenges working under the domineering Alamelu, whose interference worsens his sense of helplessness. The tension escalates when Alamelu insults Sekar’s friends at a formal event, provoking him to decide to leave with his family. Bama, eager to preserve the peace, tries to soothe Sekar, but an adverse incident occurs: Alamelu pushes Bama into a room, causing her to faint. Mistakenly believing Bama is reluctant to go with him, Sekar leaves with Pappi for Singapore, where he takes on the role of an estate manager, leaving Bama behind.
Years later, Sekar returns to Madurai, where Pappi joins the same school as Lalli. During this time, a dance teacher named Nirmala and her mother, Sogusu, plot to exploit Sekar. Meanwhile, Sundaram, who has fallen on hard times and becomes unemployed, tries to help Sekar reunite with Bama. Nirmala and Sogusu move into Sekar’s house, causing additional tension. During a school picnic, Lalli and Pappi—who are unaware of their relationship—end up sharing a room. This unexpected closeness reveals the undeniable truth that they are twin sisters, uniting the family in a new, emotional bond.
In a troubling turn, Sekar falls seriously ill, and Nirmala takes advantage of his weakened state by giving him alcohol. Under the influence, Sekar is manipulated into pursuing Nirmala, and he later falls unconscious in her presence. Nirmala and Sogusu then stage an incident suggesting Sekar had consensual relations with Nirmala, leading Sekar to believe he has fathered a child with her. This misunderstanding threatens to tear the family apart and prompts Sekar to solemnly promise to marry Nirmala—to preserve her reputation.
Meanwhile, the twins, Lalli and Pappi, decide to swap identities to protect each other. Lalli disguises herself as Pappi and stays with Sekar, while Pappi takes on Lalli’s identity with Bama. The twin sisters later uncover Nirmala and Sogusu’s true motives and their manipulative plans. Nirmala’s true colors are revealed, and Lalli, with Pappi, confronts her. Things escalate when Nirmala pushes Lalli, causing her to faint, pushing the situation further into chaos.
Sundaram, having learned about the twins’ identity swap, warns Sekar, who becomes angry and rejects the entire truth. Bama, devastated, tries to plead for forgiveness, but Sekar, feeling betrayed, decides to keep both girls but asks Bama to leave. She chooses to wait outside the house, while the children, locked inside, pray for their parents’ reunion, calling upon Murugan at the Palani temple, as per a prior suggestion. Their plans to reunite are threatened when Sogusu, seeking to take advantage of the situation, aids them in escaping from danger.
In the climax, Sogusu sends a killer under false pretenses—claiming to be their bodyguard—to eliminate the twins. Sekar, who had earlier overheard Nirmala and Sogusu plotting to murder the children for financial gain, rushes to rescue them. He discovers the trap just in time, as the assassin is confronted by a snake and killed, preventing further tragedy. The story concludes with the family coming back together, stronger and united after overcoming all these trials and misunderstandings.
Throughout, Sekar's unwavering love for his family, Bama’s resilience, and the twins’ clever attempts at protection highlight themes of loyalty, family bonds, and perseverance amid adversity. This complex family drama, filled with emotional moments, misunderstandings, and ultimately reconciliation, offers a heartfelt look into the struggles faced by ordinary people striving to keep their family united against all odds.
