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 despite 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, the police find a selfie clicked by a couple nearby with either Ezhil or Kavin in it. Both Ezhil and Kavin are brought in and investigated without their knowledge of each other's existence. Gopalakrishnan, an inspector who shares an old rivalry with Ezhil, tortures him. Ezhil reveals his car broke down and a call taxi driver helped him, as he didn't have the repair kit.
SI Malarvizhi interrogates Kavin, who cites various laws to escape torture. She reaches out to Akash's friend and shows him the photograph of Ezhil/Kavin, but he refuses to recognise 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 Kavin interrupts. The two violently fight, hurting everyone and vandalising the station in the process. Their
DNA reveals Ezhil and Kavin to be identical twins who confess to the same crimes. They parted ways when their parents divorced and Kavin went with his mother, who gambled a lot and eventually committed suicide. His father takes Kavin in but gets into a violent fight with him and Ezhil, leading to their admission to a mental institution. Kavin became interested in studying law but left due to his lack of college ethics. One day, Kavin left Ezhil's missing ring for Deepika and the police beat up Kavin. Ezhil realised his mistake and vowed to seek revenge. Gopalakrishnan still wants to frame Ezhil, but the call taxi driver who helped him confirms he was stuck on the night of the murder and paid Suruli's debt with gambling money. The sessions court acquits Kavin and Ezhil to protect the innocent from punishment. Gopalakrishnan retires without regaining his revenge. Meanwhile, Malarvizhi discovers Deepika's photo in Akash's case. She inquires with his friend about the girl he was infatuated with. In a flashback, Ezhil murdered Akash for drugging, kidnapping and raping Deepika out of his childhood lust before killing her. He also bribed the police to drop the case. Kavin helps Ezhil by getting into trouble and officially arrested to throw off the police. Later, Kavin meets Ezhil on the highway and explains how Malarvizhi can't reopen the case as she created a fake witness to help Ezhil and could herself get arrested, having done this once, which resulted in her suspension. Ezhil hands him over a photograph of them with their mother and tells him he is going to
Mumbai and later to
Copenhagen, never to return. Having sold all of his property in India, Ezhil gives a 50% share to Kavin as a tribute. After his marriage with Ananthi, Kavin realises his lack of trust in his mother prompted her to kill herself. He promises to do better with his wife. In a mid-credits scene, some investigating officers appear for a documentary shooting. One of the investigating officers calls the case unprecedented before someone tells him similar cases occurred in other countries. == Cast ==