In Coimbatore, Mayilsamy (Sathyaraj) is a pickpocket who is determined to make it big in life, by hook or crook. After being released from jail, his friend "Palladam" Bhaskar (Dhadha Muthukumar) advises him to go to Chennai and to join the gang of Kota Subramaniam (Ponnambalam). In the meantime, Kota Subramaniam who is in Coimbatore pressures the innocent village belle Pappu (Devayani) to marry him. Mayilsamy then comes across Kota Subramaniam, he beats him up and steals his money. A politician (Senthil), who witnessed the scene, asks Mayilsamy to marry Pappu in exchange for money promised by the government for those who marry girls from financially weak families. Mayilsamy marries her and deserts her soon after. In Chennai, Mayilsamy tries to find Kota Subramaniam. The petty thief "Suitcase" Subbu (Vivek) who used to steal suitcases for a living is now cheating under the name of Dr John Britto, a psychiatrist doctor. When Mayilsamy tries to escape from the police, he ends in the asylum of Dr John Britto. Mayilsamy who knows about "Suitcase" Subbu's secret lies him that he is the real Dr John Britto and he decides to keep "Suitcase" Subbu as his assistant. Puppy (Mumtaj) is a wealthy heiress and a mentally ill woman. Her parents, who are hell-bent on saving their family's prestige at any cost, do not want people to know about their daughter's mental illness and they hate each other. Mayilsamy who comes across Puppy decides to become her personal doctor and plans to marry her. Puppy is in fact faking as a mental patient to bring her parents together. Thanks to Mayilsamy, Puppy's parents reconcile and now want Mayilsamy to marry their daughter Pappu. Pappu falls in love with Mayilsamy. In the meantime, Pappu comes to Chennai looking for her husband Mayilsamy and "Suitcase" Subbu decides to help her. Mayilsamy eventually realises his folly. He decides to live with his wife Pappu and to make an honest living. He also apologizes to Puppy for playing with her feelings.