Ezhil, is a civil engineer from IIT Madras, while his lookalike Kavin, is a gambling thief who deceives people along with his sidekick Suruli. Ezhil’s love interest is an IT girl Deepika, while a girl named Ananthi, loves Kavin, unaware of his real identity. One day, Kavin tries to help Suruli pay his debt by extracting money from Ananthi through lies, but she helps him in spite of knowing the truth.
After taking the money, Kavin is enraged, and so is Ezhil after a party. That night, one of them breaks into a house and attacks the owner Akash, stabbing him to death. The next day, Kavin frees Suruli by paying his debt and wins Ananthi’s trust by returning her money and telling her the truth. However, as the investigation of Akash’s murder proceeds, a selfie clicked by a couple nearby is found with either of Ezhil or Kavin in it. Both Ezhil and Kavin are brought in and investigated without their knowledge of each other’s existence.
Gopalakrishnan, inspector who shares an old rivalry with Ezhil, tortures him. Ezhil reveals his car broke down, and a call taxi driver helped him. Kavin, on the other hand, cites various laws to escape torture. Sub-inspector Malarvizhi, is assigned to solve the case. She reaches out to Akash’s friend and shows him the photograph of Ezhil/Kavin, but he refuses to recognize him. She also questions Suruli and tells him not to leave the city without permission, but he secretly escapes.
Malarvizhi then learns of the rivalry between Ezhil and Gopalakrishnan; Ezhil helped the latter’s daughter elope with her lover, much against her father’s wishes. The forensic expert informs Malarvizhi about a hair sample recovered from the crime scene and how it doesn’t match anyone else in Akash’s home. At the police station, Ezhil tries to escape but is interrupted by Kavin. The two violently fight, hurting everyone and vandalizing the station in the process.
Kavin and Ezhil are revealed to be identical twins after their DNA is found identical, and both confess about the same; they parted ways when their parents divorced. Kavin went with his mother , who used to gamble a lot, but wouldn’t refuse anyone who asks her help, and one day tried to convince him that she’d give up gambling, but instead committed suicide.