The film opens with a renegade sniper named Craig, (Vikranth) who assassinates an army officer from a long distance and is given a new assignment by a traitor (Avinash) to finish off an ISRO scientist named Abdul Kamaal (Sharad Haksar) within 30 days. The story then shifts to Kambam, where a PT teacher named Thulasi Raman (Sathyaraj) leads a peaceful life with his son Sethu (Udhayanidhi Stalin), wife (Pragathi), and daughter. Sethu, who works as a librarian to retired Colonel Matthews (Rajesh), meets a kleptomaniac named Nandhini (Amy Jackson), who steals books from the library. After a few altercations, the two fall in love. Craig, for some unknown reasons, lands in the hill town and is seen wandering and taking photographs of Matthews. Meanwhile, Thulasi Raman complaints about a political based bar owner named Kandhan (Mime Gopi), and in an ensuing fight, Sethu comes to his rescue by bashing up the goons. Mysteriously, the corpse of Kandhan is pulled out of a waterfall, and a ring belonging to Thulasi Raman is found in his hands. The police then arrests Thulasi Raman. Sethu takes it upon himself to clear his father's name and set out to find the real killer.