Kuzhandaiyum Deivamum

Chandrasekar 'Sekar', Bama, and Sundaram are college-mates studying in Madurai. Bama's parents own a bus company, and Sekar survives on a scholarship provided by Ramalingam due to family connections. Sekar and Bama fall in love despite her parents' objections, especially Alamelu.

Alamelu agrees to their wedding after recognizing Sekar’s intelligence, and Sekar moves into Bama’s house. Sekar is appointed as the bus company manager but feels frustrated about his limited decision-making power and control over finances.

A year after their marriage, Bama gives birth to twin daughters, Lalitha ('Lalli') and Padmini ('Pappi'). Sekar continues to struggle under Alamelu’s dominance, which causes tension in the household.

Sekar, feeling suffocated, asks Bama to leave with him, but she hesitates due to family reasons. Bama is pushed by Alamelu into a room and falls unconscious, leading Sekar to mistakenly believe she is reluctant to leave.

Sekar leaves for Singapore with Pappi and becomes an estate manager, while Bama unsuccessfully tries to find them through advertisements. Meanwhile, the family remains unaware of the true circumstances of Bama’s condition.

Sekar returns to Madurai years later, and Pappi joins her school. Nirmala, a dance teacher, and her mother Sogusu, plot to exploit Sekar and manipulate his relationships, introducing new conflicts.

During a school picnic, Pappi and Lalli fight and are forced to share a room. They bond and realize they are twins, but attempt to swap identities to hide their true relationships from others.

Sekar, after being served alcohol by Nirmala, becomes drunk and is tricked into believing he has impregnated her. Nirmala and Sogusu stage an incident implying they had sex, leading Sekar to promise marriage to Nirmala out of shame.

Pappi and Lalli swap identities, causing confusion as they try to expose Nirmala’s manipulations. Nirmala pushes Lalli, who fainted, further complicating the situation. Sundaram seeks to reveal Nirmala’s true nature but faces Sekar's anger.

Bama and Pappi learn about the twin identity swap and rush to meet Lalli, who regains consciousness and reveals her true identity. Sekar, regretful, decides to keep both girls but banishes Bama, who waits outside, while the children pray for family unity.

Sogusu sends a killer with a false promise of protection to the girls. Sekar, Bama, and others realize they're in danger, and Sekar eavesdrops on Nirmala and Sogusu’s plans, discovering an attempt to kill the twins to usurp the family wealth.

Sekar, in a rage, rushes with Bama to Palani to rescue the twins. The killer catches up with the girls, but a snake kills him before he can harm them. The entire family is finally reunited, overcoming the various schemes and dangers.