A great train robbery takes place near Chennai and three robbers Jambu ('Major' Sundarrajan), a Hindu, Joseph (R.S. Manohar), a Christian, and Naseer (S.V. Ramadas), a Muslim steal the jewels of the passengers at gunpoint. They continue stealing from various shops and hotels and their atrocities become the talk of the city.
The three enter a rich man Prabhakar's (Krishna) house, kill everybody and steal the money. They see a young and loving child there and Jambu starts to like her. The other two do not show any affection but Jambu decides to bring her along with him. The police arrive but by then the three escape with the child. The police find that all the robberies and the killings were carried out by the same set of robbers and announce a reward of Rs. I0,000/- to anyone who can provide a clue to catch them.
At their hideout, Jambu gets attached to the child whilst the other two believe the child has come to kill them. But the child, through her loving attitude and respect for their religions, makes the other two also like her. Now, all the three believe that the child is God like and give her all the affection they can.
Their problem begins when the child does not eat and demands the Aaya (maid) to feed her. They try but the child cries for the Aaya Gouri (Padmini). Left with no choice, Jambu travels to bring her.
Police Inspector (S.A. Ashokan) is investigating the case and enquires Gouri about why she, who usually spent every night with the child, left the child alone that specific night. They suspect that she was hand-in-glove with the robbers and keep her in their custody. Jambu comes to know Gouri's address from two fellow passengers. He meets Gouri's mother as her brother Manickam, convinces everyone that he is their close relative including the police officers, and then takes Gouri with him forcefully, jumps off the train, and escapes from the police.
Gouri is happy to see the child but is shaken about being with the robbers who killed her master. She takes care of the child and also cooks and attends to them. She tries to kill them by mixing poison with milk but they find that out and beat her. She then plans to split them and escape with the child. She tries to entice them and Joseph and Naseer fall for it. But Jambu understands her game and puts sense into the other two. Her plan fails again.
The three decide that Gouri should be out of the life of the child. So they demand her to behave in a manner that the child hates her. She does not agree because she has brought up the child. Jambu gets more attached to the child and so does the child. He starts believing that the child will live without Gouri and decides to kill her. Gouri overhears this and escapes with the child. However, they soon find out and chase her. The child starts shouting and to make her silent, Gouri shuts her mouth which leads to her wheezing and heart problem. They catch them and she asks for their help to bring Doctor Ramanathan (T.K. Bhagawathi), who knows the child's health condition. Joseph goes in the disguise of a Sardar and visits Ramanathan who is at a wedding and convinces him to come with him. The police who were at the marriage venue find it fishy and follow their car. The police try to shoot and stop them but Joesph somehow escapes with the doctor.
Joseph and the doctor reach their hideout and Ramanathan understands the dire situation. He attends to the child and stops treating her saying that the child will anyway die. The three beat him, threaten him but he refuses to treat the child and says that they will become the reason for the death of the child. The three get emotionally disturbed and beg his help. He puts up a demand that he will attend to the child only if they agree to surrender to the police for their crimes. The three express their fear of losing the love of the child if they surrender. For which Ramanathan assures that he will fight for them in the court and also ensure that the child comes and meets them every day. The three agree to surrender and Ramanathan attends to the child.
Naseer goes to the city to get medicine. The shop keeper informs the police and they arrive to catch him but he manages to escape. Ramanathan treats the child and the three pray for her recovery. Finally, the child recovers and asks for the three uncles instead of Gouri. The three get attached to the child and decide to leave all their wealth behind and move away with her. They get surrounded by the large number of police. The three attack the police courageously. Ramanathan and Gouri manage to escape with the child. Joseph is injured and when they realize that the child has been taken away, they decide to escape somewhere in order to get her back. They manage to escape and hide and the police is unable to trace them.
Ramanathan convinces the police about the love the three have for the child. The police assure that the child can meet them in jail and also not to shoot them when they surrender. Ramanathan now asks the child to speak in the mic and the child calls for the three uncles. They hear her and surrender to the police. Ramanathan assures to take care of the child and bring her to meet them regularly. The three are arrested by the police and the child follows calling them out.
[from the book Pride of Tamil Cinema: 1931 to 2013 by G Dhananjayan, Blue Ocean Publishers]