Narayanan (Namo Narayana) is the son of Central Minister Pandiyanar (G. Gnanasambandam). Narayanan uses his father's name to make money by corruption, much to the latter's dismay. One day, some goons try to kill a man in daylight, as instructed by Narayanan. The man is lying in a pool of blood, and a local person witnesses this and informs this to the ambulance. The ambulance driver is Maha Vishnu (Samuthirakani), a kindhearted man who has never let anyone whom he has taken in his ambulance die. Vishnu admits the man in the hospital, and he is saved. Narayanan is angry with Vishnu for saving his enemy, for which he replies that saving the lives of people is his duty.

Vishnu is married to Bagalamugi (Sunaina). He has a father (Vela Ramamoorthy) and sister Mahishasuramardini (Arthana Binu). The latter is stalked by Vicky (Vikranth), a drunkard and jobless youth who happens to be a friend of Vishnu. Vishnu convinces Vicky to reform and attend the medical technician course. Vicky completes it successfully and saves people's lives, earning the love of Vishnu and his family. Mahi has a friend named Gowri (Gouri Nair), who is stalked by Narayanan's brother Chinna Pandi (Soundararaja), and she beats him in a bus. Insulted by this, Chinna Pandi beats Gowri up with a wooden log. Enraged, Mahi and the students kill him. Vishnu arrives with his ambulance to admit Chinna Pandi to the hospital. To avoid traffic, he takes the outer bypass, infuriating Narayanan. Chinna Pandi succumbs to the injury. Narayanan blames Vishnu for this and beats him up, but he is saved by the public. Narayanan vows to kill Vishnu.

Vishnu gets mad after his father loses his hearing ability and his wife suffers a miscarriage. Deeply saddened by this, he confronts Narayanan, who pleads that he is innocent. Vishnu believes that being a common man, he cannot do anything against a powerful man who has political support. Narayanan bribes Inspector Uthaman (Anil Murali) and three government officials and has them under his control. Vishnu is helped by Sub-Inspector Rahman (Poraali Dileepan). Vishnu plans to destroy Narayanan and bring him to justice. He gathers all the details of the properties owned by Narayanan and a video footage of him insulting Uthaman and the government officials while bribing from Narayanan's auditor, who helps Vishnu because he once saved his wife's life. Vishnu realizes that Narayanan used Pandiyanar's name to earn huge amounts of money and buy so many properties by corruption. Vishnu sends the evidences them to IT, Vigilance, and other departments. He also sends the video footage to Uthaman's wife and the government officials' wives, who lose respect among their family. Uthaman and the government officials decide to stop supporting Narayanan for his further actions.

The IT department raids Narayanan's house, confiscates all of his belongings, and arrests him. Narayanan tries to escape but meets with an accident. While he is struggling, Vishnu comes with his ambulance and saves him.