Krishnaswamy is a widower living with his mother-in-law Saraswathi Ammal, daughter Kaveri and son Bharani in a village near Kumbakonam. Dhanush, a con artist from Madras, lusts for Krishna's prosperity and asks him to join his chit fund business. Krishna is initially reluctant; however, when a rich friend from abroad visits his house, he too wants to be rich like them. Hence he agrees to Dhanush's proposal and arrives at Madras, unaware of Dhanush's tricks. When Dhanush swindles the chit fund money, Krishna is implicated and wrongfully convicted.

Krishna finds that even his future father-in-law Panjapakesan is also in jail for the same reason, whose daughter is Yamuna, a nurse. He advises Krishna not to be angry if the jailor is cruel, as he might be released sooner if he is submissive in the jail. During Krishna's tenure in jail, Yamuna takes care of his family. Due to unavoidable situations, his mother-in-law dies, and his children go missing. Krishna learns this after coming out from jail suffering unnecessary hardships.

Krishna finds his son with street artists and gets him back. He later learns that his daughter is in Calcutta, at a red-light district called Sonagachi. When Krishna was arrested, Kaveri had attained puberty, and three months later, Saraswathi became sick. Kaveri and Bharani go to Dhanush asking for financial help. Dhanush takes them to his higher boss, so that the virgin Kaveri could sleep with him to get money. Though the boss provides money to Dhanush for Saraswathi's treatment, he chases out Bharani with his dog and keeps the money for himself. It is implied that Kaveri is raped by the boss and is child trafficked, ending up in Sonagachi.

Krishna goes to Calcutta with his father-in-law and tracks down his daughter. Unable to bear the grief, he grabs her and tries to escape, while the pimps there beat him severely. The elder sex-workers/madam make a truce and insist that Krishna take Kaveri, while they would work extra hours to pay the pimps for the loss of Kaveri.

After returning from Calcutta, Krishna wants to start a new life with Yamuna, but his friend in the police, Muthusamy tells him that Dhanush has planned to jail Krishna further by plotting a murder case against him, he would be arrested the next day. Also, Krishna overhears his daughter blabbering in her sleep not to rape her. He is heartbroken due to the state of his children, so he decides to curb the root of all sin and grief against Dhanush, and goes to seek revenge.

Krishna learns that Dhanush is just a pawn in the big game of cheating. He not only kills Dhanush, but also Venkatachalam, the main person who was behind this game; at the cost of his left arm. Krishna is sentenced to 14 years of imprisonment and comes out a contented man, to see his daughter married to Muthusamy's son and having a child, and his son being a grown-up man. The whole family moves back to their native village.