Sethupathi (Kamal Haasan) is an honest and upright police officer. When he arrests four bigwigs, Dharmaraj (Nagesh), Francis Anbarasu (Delhi Ganesh), Nallasivam (Nassar) and Satyamoorthy (Jaishankar), they escape justice easily and return to take revenge. They kill him and poison his wife Kaveri (Srividya). She escapes and gives birth to twins with the help of another woman Muniyamma (Manorama), but the babies are separated and each woman believes that the other is dead because of the events happening after the birth. One of the twins, Raja (Kamal Haasan) grows up as a mechanic with Muniyamma, while the other twin, Appu (Kamal Haasan), a dwarf,[a] grows up in the circus with his mother. Appu falls in love with the daughter (Rupini) of the circus owner (T. S. B. K. Moulee), mistakenly thinking that she was asking him to elope with her. But she actually had asked him to be witness to her marriage with her fiancé (Anand), which was not approved by her father. Heartbroken over this and insecure about his height, he tries to commit suicide, but is prevented by his mother, who then reveals the reason that his dwarfism might have been because of the poison force-fed to her when she was pregnant with the twins. This leads Appu to learn about his father's murder and decides to avenge him. Meanwhile, Raja falls in love with Janaki (Gouthami), who happens to be Satyamoorthy's daughter. As Raja resembles Sethupathi, Sathyamoorthy and his 3 friends gain interest in Raja. Francis is fishing in a lake. Appu uses one of his well trained circus Indian Spitz puppy to lure Francis to an abandoned building, and reveals his identity to him. Francis smirks when he sees that Appu is a dwarf and cannot hurt him due to his size. But Appu uses a Rube Goldbergian contraption to kill him, and the dead body falls in a lorry covered with hay. Raja and Janaki have car trouble and hitchhike a ride in the same lorry, but are oblivious to the dead body. The lorry driver (Kavithalaya Krishnan) d