M. G. Ramachandran, Jayalalithaa, Rajashree
M. S. Viswanathan
Twins Sekhar (Master Sekhar) and Anand (Master Sekhar) along with Mangalam (Pandari Bai), their mother witness their father (S.V.Ramdass) being killed by escaped prisoner Nagappan (M. N. Nambiar), and are grief-stricken. This prompts the family to leave to Chennai in order to pursue a new life. But when Sekhar gets down from the train to fetch some water, it leaves without him. Nagappan arrives and kidnaps Sekhar, who is raised as a criminal, unaware that the same man killed his father.
Years later, the now-grown up Sekhar (MGR) who calls himself "Babu", is an established criminal and is the most wanted man in the city. On the other hand, Anand (MGR) is a club-dancer and neither are aware of each other's existence. During a police encounter, Babu is fatally wounded and seeks shelter in Mangalam 's house, although he does not recognise her as his mother. He develops a soft corner for her, but when Nagappan (become Boobadhi, so-called respectable one owner of cabaret and employer of Babu) finds out about this, he tries to eradicate the kind-self out of Babu.
During another police encounter, Babu is again fatally wounded but becomes insane this time, also becoming amnesiac. D.I.G. Mogan (Major Sundarrajan), the local inspector then comes across Anand, and after seeing the striking resemblance between him and Babu, advices him to act as Babu in order to get all the secrets of the gang and have them arrested. Anand agrees, but later realises Babu is his brother. Anand's girlfriend Jaya (Jayalalithaa) sees him having lot of money in a brief-case, and the police chase him. Unaware of the truth, she thinks he has turned into a criminal, and refuses to speak to him. Anand's mother also comes to know of this, and becomes heartbroken. However, Mangalam and Jaya soon reconcile with Anand after learning of the truth, and they both also find out that Babu is his brother.
Babu's girlfriend Asha (Rajashree) later finds out that Anand is impersonating Babu, but he surrenders to her and explains about Babu's medical condition, subsequently revealing himself as Babu's brother. Asha forgives him and the duo subsequently team up to defeat Nagappan and his men. Babu later escapes from the prison to kill Anand when learning about him, but is cornered by Jaya who tells him that Anand is his brother. Babu refuses to believe this, and kidnaps Jaya. He is later stopped by Mangalam, who makes him realise that he is her son and Anand is his brother, Babu finally realises it. Remembering that Nagappan killed his father, he teams up with Anand to defeat Nagappan, who is later arrested. Subsequently, Babu returns to being "Sekhar", and reunites with his family.