Sivakumar is a meek person who owns a mobile sales and service center in Madurai with his friend and sidekick Ganesan. He falls in love with his father's tenant Malarvizhi Chidambaram. His father Kalyanasundaram , a retired government employee, shows much care on Siva's elder brother Nagarajan, an honest government officer. Meanwhile, there is a big mafia gang led by Simmakkal Ravi, who rules Madurai with an iron fist. Sethu, a friend of Siva, helps him woo Malar by beating up men who were harassing her. Later, Sethu also helps his ex-lover Amudha escape from Ravi's chief henchman Bharani, who was harassing her, by stabbing him in the stomach. Siva tells Sethu and Amudha to flee Madurai. Meanwhile, Nagaraj's wife becomes pregnant with their second child. Nagaraj confronts Ravi over the deaths of workers at his quarry, which is deeper than the legal limit, and shuts it down. An angered Ravi stages a road accident and kills Nagaraj. At the hospital, a frightened Kalyanasundaram is threatened by Ravi's men to keep quiet about the incident and they forge Kalyanasudaram's signature for a document stating that Nagarajan was driving under the influence, and the father discovers that Ravi killed Nagaraj. Later, Siva confides to Ganesan that he had discovered the truth about Nagarajan's death. The grieving Siva and Kalyanasundaram draw up separate plans to eliminate Ravi, without each other's knowledge. Kalyanasundaram pays ₹3,000,000 ($50,000) to a prisoner to organize a hit squad, while Siva, through Ganesan, gives Ravi and his assistant hacked smartphones so as to track their calls, and monitors Ravi's activities closely for a year, biding his time for the right moment. Siva plans to kill Ravi when he visits Coonoor to meet a minister friend of his. However, as he prepares to attack, the hit squad attacks Ravi in the same spot. As Ravi fights back, Siva runs in to try and kill Ravi but is seen masked by Bharani. Ravi kills all of the hit squad members and finds out who hired them. In the meantime, Siva gets engaged to Malar. Ravi forces the hit squad organizer to tell his client that he will return the money at a bus stand so they can capture and kill the person who tried to kill him. To retrieve his money, Kalyanasundaram goes to the bus stand and is chased after by Ravi's gang. He falls unconscious due to the health problems and is almost captured before a masked Siva rescues him from the goons and takes him to the hospital, without revealing to the staff that he is his son.

There, Siva and Ganesan, who had retrieved the money, weep after hearing Kalyanasundaram lament his failure to his advocate. Siva then continues to follow Ravi and makes a plan with Ganesan to kill him at a temple festival. Ravi, suspecting a member of the general public, has the police commissioner round up all male family members of civilians whom he had killed to discover the would-be killer. Siva learns that Ravi will be meeting in a theatre, and so Siva, against Ganesan's advice, goes to the theatre bathroom to kill Ravi. However, he is evicted by one of Ravi's men and leaves his sickle in the stall. Bharani, however, recognises Siva from their past encounters, while Ravi notices the sickle and chases Siva, who escapes. However, he meets Amudha, who tells him that after Siva told Sethu to leave, the police stopped him and handed him over to Ravi. Bharani killed Sethu right in front of Amudha. When Ravi's henchman corner them, a furious Siva manages to kill them all. An angered Bharani attacks Siva, only to be killed by Siva, thus avenging Sethu's death. When Ravi arrives and sees his dead men, Siva kills the last of them and attacks Ravi. After a tense and fierce fight, Ravi is seriously wounded. The police arrive at dawn, after Siva takes Ravi to a well and leaves him there to die, telling him that he represents all the innocent people whom Ravi has killed and that Ravi will watch himself die. Siva is then married to Malar. The news mentions how Ravi's partially-decomposed body is discovered after Siva gives an anonymous tip to the police. After Siva secretly tells his father his role in all the events, Kalyanasundaram embraces his son with joy and takes a walk with his grandson.