In Kolkata, prisoner Kathiresan "Kathir" (Vijay), a petty criminal, helps the police capture an escaping prisoner Vivek Banerjee (Tota Roy Chowdhury), but he himself escapes afterwards. He goes to Chennai and decides to escape to Bangkok with his friend and fellow-criminal Ravi (Sathish). However, he drops this plan after meeting and falling in love with Ankitha (Samantha Ruth Prabhu) at the airport, who dupes him into believing that she wants to marry him after realising that he is having a crush on her. Later, Kathiresan and Ravi notice a man who resembles Kathiresan named Jeevanandam "Jeeva", being shot by a group of thugs. They admit him to hospital, following which Kathiresan decides to impersonate the injured Jeevanandam to escape from the police. Under the name of his doppelg nger, Kathiresan and Ravi enter an old-age home run by Jeevanandam with the aim of collecting 25lakhs (which is meant for the inmates of the old-age home) for their Bangkok trip, until he learns about his doppelg nger's mission. Jeevanandam is a communist ideologue and a post-graduate in hydrology from the arid village of Thanoothu in Tirunelveli district who had discovered groundwater under some lands of the village which could be used as an irrigation source not only for the village, but for the entire Tirunelveli district and the neighbouring Thoothukudi district as well. But, an MNC owned by Chirag (Neil Nitin Mukesh) cheated the villagers into giving their lands for the construction of a factory. Jeevanandam was arrested by the police and the six villagers to convince the media for the release of Jeevanandham commit mass suicide. On learning of the plight of Jeevanandam and the villagers, Kathiresan decides to fight for their cause while still under the name of Jeevanandam.