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 (Tamil actress)), 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 dwarfism, grows up in the circus with his mother.