Based on horrifying true incidents that happened between 1985 - 1995 in Chennai, still remembered as 'Once upon a time in Madras'.
Shankar, a small-time smuggler challenges his boss Ramajayam, who is involved in the business of bootlegging. With the help of police officer Kathiravan, Shankar succeeds to ditch Ramajayam and hands over the liquor to Vinayagam. Shankar comes across Chandrika, a cabaret dancer, and fights with the goons who try to misbehave with her. Chandrika gets impressed with Shankar and they fall in love.
During Aasaithambi’s party, Ramajayam has a tiff with the minister. Kathiravan guides Shankar to take advantage of the situation and conquer Ramajayam and Reddy's business. When Aasaithambi who comes to rescue Ramajayam and Reddy at the police station, Shankar insults him. Shankar takes control over the city's entire illicit liquor and brothel business
Shankar, who has fallen in love with Chandrika, ill-treats his wife Sumathi. When the situation becomes worse, Sumathi leaves the house. Sudalai advises Shankar to be careful with Chandrika but he does not bat an eye. Meanwhile, Kathiravan visits Shankar as he fears of losing his power over Shankar.
Sudalai shows Chandrika’s picture to the minister who gets tempted to spend a night with her and requests Shankar to arrange for it. When Shankar denies his request, the minister uses his power against Shankar. Kathiravan advises Shankar to fulfill the minister’s demand. When Shankar finds out that Sudalai was behind this, he decides to kill him.
When everything gets into its place and Shankar's men are released, Ramajayam sends his men to destroy Shankar's brothel. An enraged Shankar picks up Ramajayam’s man Govindharaj, kills him and buries him in the walls of his house.
When an inspector comes to investigate about Reddy’s death, people show their support for Shankar. When Govindharaj’s widow comes to complaint about Shankar, Kathiravan tries to ignore her. During Shankar’s birthday, Kathiravan comes and expresses his interest in Chandrika. This irks Shankar and kicks him out of the house.
When Thalaivar demands to sleep with actress Kamnini, Shankar refuses to fulfill his wish. Meanwhile, Shankar gets to know about the Babu and Lalitha betraying him and loses his cool and goes on a killing spree. He kills all of them and buries them in his house. However, Babu manages to escape and save his life.
Due to the pressure from the Governor, Govindharaj’s case gets transferred to CBI. Kathiravan brainwashes Babu and convinces him to become approver. The police reach Shankar’s house and gather proof against him.
During his time in prison time, Shankar gets a few inmates to help him plan his escape. Shankar falls in love with Devi, wife of a fellow inmate, and includes her in his plan. With the help of Jayavel Shankar escapes from prison.
After escaping from the prison, Shankar gets hold Kathiravan but he leads Shankar to Babu and escapes. Shankar confronts Babu and later escapes to Odisha to hide at his father's house but eventually gets caught. Shankar is sent to back to prison where he meets his fate.
