Sakthivelu alias “Velu” Nayakan is the son of an anti-government union leader (Kitty). The child, Velu, is tricked by the police into locating his father, and then witnesses his father’s death in a police shootout; he later kills the person who was the cause of his father’s death and escapes to Bombay.Stranded and homeless in the big city, he meets two boys who take him to their home in the suburban slum area of Dharavi. Over there, a Muslim fisherman raises Velu; the former is also a small-time smuggler known for his generosity among the slum dwellers. Upon locking horns with a senior crime lord, a corrupt local police officer named Kelkar arrests the fisherman on smuggling charges and subsequently murders him. In revenge, Velu, now a young man (Kamal Haasan) kills the inspector, but as an act of remorse, he decides to adopt Kelkar’s mentally challenged son Ajith and raise him as his own. With this act, Velu soon becomes a godfather of that area, engaged in smuggling and at the same time, supporting those who are in need of help. When he visits a brothel, he meets Neela (Saranya Ponvannan), a destitute school-girl-turned-prostitute, and is impressed by her dedication to continuing studying despite being a prostitute; he later marries her.As his popularity increases, he starts eliminating rival gangs. Selvam(Janakaraj) and Iyer (Delhi Ganesh) are his close associates in these activities. Once when nobody is able to bring a contraband parcel out of a ship, Velu brings it ashore with Selvam’s help by hoodwinking the Customs officials. The Reddy Brothers, who were unable to bring out the same contraband, lose to Velu as a result. Angered, they make an assassination attempt on him and his family; Neela dies in the attack. Velu retaliates by killing every member of the Reddy family. Worried about the safety of his son Surya and daughter Charumati, he sends them to Chennai.Several years later, Velu becomes the biggest mafia leader of the city with a large number of followers, including a grown-up Ajith (Tinnu Anand). His children Surya (Nizhalgal Ravi) and Charumati (Karthika) return to Bombay as adults. Despite Velu’s reluctance, Surya follows his father’s profession. Charumati is upset about this development and expresses her anguish to her father but in vain. When one of Velu’s associates turns approver, Surya hires an assassin who kills the approver in the court. In his excitement, the assassin comes to meet Surya personally at a petrol station to report his deed. When the police surround them, Surya burns the petrol station to destroy all the evidence and escape but is killed in the process. A distraught Charumati blames Velu for her brother’s death and leaves him.Several years later, Velu continues to dominate the area. A new ACP (Nassar) takes charge of the area and starts taking severe action against Velu’s activities. He arrests many of Velu’s men. When Velu goes to the ACP’s home to caution him, he discovers that Charumati is the ACP’s wife and that they have a son. Understanding the situation, Velu leaves. The ACP continues his punitive actions against Velu; however, he is unable to arrest him since the people in the area protect him and even set themselves on fire when the police approach his hideout.Worried about his people dying, Velu calls Charumati and advises her to ask the ACP to arrest him after he completes the ceremony relating to Neela’s death anniversary the next day. By then, ACP comes to know that his wife is Velu’s daughter. When he reaches home, Charumati advises him to arrest her father the next day. The ACP arrests Velu, but due to lack of evidence, he is acquitted by the court. An excited crowd greets Velu when they see him coming out of the court but their joy turns to sorrow when Ajith, now aware of the truth behind his biological father’s death, shoots Velu dead.