Thiyagarajan, Vikram, a medical student, heads to meet his childhood friend Varadharajan. On the way, he crosses paths with Deiva, Anita Hassanandani Reddy, a kind-hearted but mischievous schoolgirl who lives with her grandmother and is the daughter of police officer Sandana Pandian, [Nassar]. Sandana has a run-in with Thiyagarajan, but later realizes his kind-heartedness.
Thiyagarajan then gathers his friends to kidnap a politician involved in illegal activities. He soon learns that Sandana's family are neighbors with him and share close ties with his own circle. After the politician is kidnapped, Sandana is assigned to investigate the case. Meanwhile, Thiyagarajan also abducts five other people, while Sandana struggles to catch the culprit.
During this time, Nisha's friends try to molest Deiva. Unable to bear the trauma, she returns to her parents. However, Sandana is already stressed from the case and does not want to hear about Deiva's problems. Thiyagarajan helps ease Deiva's anxiety by telling her she now knows how to avoid such situations in the future. After that, Deiva, not knowing Thiyagarajan's true identity, falls in love with him.
Past: Kavitha, Jaya Seal, a studious classmate, keeps a diary about things she wants to tell Thiyagarajan but never does. Although Thiyagarajan sometimes irritates her, he also loves her. While in medical school, Kavitha discovers that a pharmaceutical company distributed expired medicines that caused a boy's death. When she tries to expose the company, she receives little support, and the boy's death remains unacknowledged. Overwhelmed, Kavitha takes her own life, but before dying she asks Thiyagarajan to deliver justice for the boy. After reading Kavitha's diary, Thiyagarajan and his friends decide to exact vengeance on those who exploit legal loopholes to avoid real punishment by using guest houses and hospitals.
Present: Sandana discovers the next target is a minister behind the pharma crimes Kavitha uncovered. He tries to protect the minister, but is kidnapped, revealing Thiyagarajan's involvement in the kidnappings. Knowing Pandian is after him, Thiyagarajan attempts to escape. When Deiva confesses her love, he reveals his identity to her. Sandana captures Thiyagarajan and puts him on trial in an open court with magistrates and an audience. They demand the kidnapped people be released, but Thiyagarajan argues that they should be punished; the magistrates deny capital punishment, saying no such penalty exists in the law. The abductees are released, and the crowd that heard Thiyagarajan's argument forms a protest that leads to the deaths of the abductees. Sandana then takes Thiyagarajan and his friends away in a van and praises his work, stating that there is a need for a law that allows for the death penalty for the truly guilty. As Thiyagarajan leaves, Deiva arrives, reminding him of Kavitha and assuring him that Kavitha is always with him, just as Deiva will be. The tale closes with Thiyagarajan and his friends leaving with Deiva.
Also, Sriya Reddy makes a brief special appearance.
