Rangan (M.G.R) the very loving brother of Thangam, though only a cart puller, dreams of educating his sister, to become a doctor. So, when he learns of his sister's love with Murali (Muthuraman), a doctor, he gets them married, in a grand manner. Murali's mother, after their marriage, learns that Thangam is the daughter of Velappan, her husband's (mill owner Karunakaran) murderer. Thangam is thrown out of the house. Rangan finds out that his father, who is still languishing in jail, had been falsely implicated. He vows to bring the real culprits to book. His fiancé Valli (Jayalalitha), helps him nab the murderers. It is proved at last that justice always wins.