Maaran is an honest investigative journalist, who follows his father Sathyamoorthy's footsteps to be honest and smart in his profession. He butts heads with senior editor Aravindan over his uncompromising principles. Though the Managing Director, Kesavan, who had been Sathyamoorthy's acquaintance, supports Maaran, he also cautions Maaran to be careful. One day, Maaran is contacted by his friend, police Inspector Arjun, who asks him to investigate the activities of prominent politician Pazhani. Maaran and his colleagues expose Pazhani's plan to rig an upcoming election by changing the EVM machines. Shortly thereafter, Maaran, his colleague and love interest, Thara, and Shwetha are attacked by thugs searching for Maaran's evidence against Pazhani, but overcome them. Shwetha and Maaran's uncle worry about his safety, but Maaran dismisses their concerns.Soon after, Maaran receives a video of his sister terrified and tied to a chair, then coordinates to an abandoned building. When he arrives, he finds the chair and his sister burning. Shocked and traumatised, Maaran falls into depression, until Thara urges him to take revenge for Shwetha's death. Maaran reads his sister's autopsy report and visits her boyfriend, who reveals that he had been with Shwetha when she had been abducted. His description of the attacker and his car leads Maaran to suspect Pazhani, but Arjun refuses to investigate as the evidence is purely circumstantial. Maaran and his uncle fake the kidnapping of another girl and plant evidence against Pazhani to instigate the police to search his home.Pazhani confronts Maaran during the search, and tells him that he only wanted Maaran's evidence from the EVM case and that he wasn't responsible for Shwetha's death. Maaran, realising that there was another person involved with the EVM scheme, He investigates further and finds a link to Parthiban. Arjun, having realised that Maaran had faked the kidnapping that led to Pazhani, refuses to listen to Maaran's conjecture. Parthiban lures Maaran to an empty building and attacks him. Maaran reveals that he knows that Shwetha is still alive. Shwetha had had a steel plate inserted into her right arm following a childhood surgery, but the corpse that had been set alight showed no signs of such a plate. Parthiban reveals that he had been entrusted by Pazhani's aide to switch out the fake EVM machines with the real machines.After Maaran's story broke, his daughter had found his involvement and confronted him. When Parthiban tells her that he only committed misdeeds in order to fund her education, the girl commits suicide by setting herself alight. Parthiban tells Maaran that he will only release Shwetha, if Maaran compromises his unrelenting honesty and claims that he faked the EVM story. Maaran agrees, but before he can do so, Pazhani and his henchmen arrive and shoot Parthiban in an attempt to clean up the loose ends on the EVM case. Maaran narrowly stops Pazhani from killing Parthiban. When Arjun and his policemen arrive, Maaran remembers his father's advice and claims that Pazhani had kidnapped Shwetha and that Parthiban had been helping him find her. Pazhani is arrested and Parthiban reveals Shwetha's location. With Parthiban's testimony, Pazhani is arrested for both the EVM scheme and the attempted murder. Meanwhile, Maaran and Shwetha share an emotional reunion, supported by Maaran's colleagues.