S. J. Surya, Simran, Manivannan, Devayani
A. R. Rahman
Pappu an eight-year old boy who is very mischievous always troubling his mother. His mother scolds him when he eats the toothpaste, urinate in bed at night. Pappu falls down on a road one day and a young woman helps him. Pappu's elder brother plans to watch adults movie with his friends in the absence of their parents and Pappu demands him to join him to which his brother does not allow him. Angered, Paapu cuts off the power which creates a short circuit at home. Pappu's mother scolds for his dangerous mischief and shouts at her husband for not stopping with one child as Pappu is troubling her a lot. This hurts Pappu and he runs away from home to jump into a river. But he is stopped by an old man and he takes Pappu to his place. The old man introduces himself as a scientist who has his own laboratory. He insists Pappu to help him in his research of transforming a child to a young man. Pappu agrees and the scientist transforms him to a young man. Pappu starts to live as a young man physically but as a child mentally and stays away from his family. The only person other than scientist who knows the truth is his child classmate friend. Pappu meets the girl at a park who helped him once he fell down on road. Innocent child Pappu helps to remove dust from her eyes, smiles at her and leaves the place. The girl is very much attracted towards him and she looks for him every day.
Pappu goes for an interview in a company under the name of Vichu. The company is toy manufacturing company and the owner who interviews him demands to have childhood memories and should be like a child to understand children's taste. Since Pappu himself is a child he grabs the job easily. Vichu is diverted to the daughter of the owner who is none other than the girl named Priya who helped Pappu once on road and whom she was helped by him at the park. Priya is surprised and happy to see him in her company. Priya-Vichu intimacy creates a jealousy for Raj another employee in the company who intends to attract her and marry her. The cold war continues when Pappu overcomes Raj's idea for a new type of bed for kids and introduces his own idea creating a successful product. Pappu meets his brother as an anonymous man and hears that his mother is very depressed on Pappu's disappearance. Pappu meets his mother who fell sick since her son got missed. She feels bad for having so strict to her child which she had done for his goodness. Pappu realised his mother's love and goes to scientist to change him back to eight-year old boy. Scientist understands his mind and he again transforms him to eight-year old boy and Pappu reconciles with his mother. But again at night he changes back to young man and he immediately rushes to scientist. But scientist does not know what has happened and both of them are shocked on Pappu's present condition.
Pappu now lives as an eight-year old boy during day time and as a twenty eight-year man during night time. Priya expresses her love to him but Pappu tells her to love a man suitable for her age. Scientist tells Pappu to accept Priya and Vichu accepts her love. Priya tortures him always to which he cannot withstand. Priya tells him accompany for a matinee show. Since Pappu is a boy during day time he cannot come. But he sees Priya waiting in anger for him in the theatre while going to home from his school along with his mother. Pappu's mother befriends Priya as they are neighbours and Priya likes small boy Pappu. Priya gets angry on Vichu's (Pappu's) absence. She finally decides to both get married. Raj kidnaps Vichu on day of marriage but Vichu changes to Pappu during daytime. The kidnappers release him as they misunderstand of kidnapping a child. Pappu transforms to Vichu and marries Priya at evening time.(Hindu marriages take place usually at mornings). Vichu though a young man by body but small boy and does not know anything about marital life. Now Vichu lives as an eight-year son to his mother during days and as Vichu, an employee in his wife's company and as husband to his wife during night time. Pappu somehow manages his mother by disappearing during nights.Priya needs a child so she intentionally shows her skin to him by intentionally removing her clothes. Priya is now pregnant and Vichu is now a child dad. Vichu once meets Pappu's (his) mother and understands the difficulties of pregnancy for a woman. Hence he takes care of his wife with full affection. Pappu's child friend demands to spend time and come to play with him but Pappu refuses as has got tight schedule as a son, as an employee and as a husband. His friends get angry and reveals the truth to Priya. Priya is shocked to hear that she is bearing the child of a child.
Priya argues with Pappu for marrying her and made her pregnant but Pappu shouts at her arrogance of having involved him in trouble in spite of his warning to marry a suitable man of her age. Pappu turns to Vichu in front of her and Priya is further shocked to see the transformation by her own eyes. But Vichu reveals that he loves her anything else in this world. Priya now gets labour pain and Vichu takes her to hospital. But on the way Vichu is stopped by Raj's men seeking revenge. Vichu overcomes the difficulties and admits her in the hospital. Everybody now comes to know the truth about Pappu and Priya gives birth to Pappu's son and she is upset on her fate of being a child's wife.
Twenty years pass by. Now Pappu is a real young man of twenty-eight years old.He still lives with Priya as her husband. He goes inside his room as young man and comes out as a forty eight-year old man who is now husband of forty year old Priya and father of twenty year old son who looks like him. Pappu calls scientist to find if he had found remedy for his transformation to which he gets a negative reply from him.
Now Pappu shall live a life as a man with actual age during dawn to dusk and live as a man with actual age plus twenty years from dusk to dawn.