The movie New is a Tamil film that follows the story of an 8-year-old boy. A scientist turns the boy into a 28-year-old man. Pappu is the name of the boy. He is always getting into some kind of trouble. When his brother does not allow him to watch a racy movie this makes him very angry. Pappu cuts off the electric supply to the home and gets in trouble by his mother. He gets upset and runs away from home. He is able to jump off of a bridge when he is stopped by an older man. The man says he is a scientist and wants to turn Pappu from a boy into a man. Pappu agrees to this deal, and while his body turns into that of a man, his mind is still a child.
Pappu starts living as a man and chooses the name Vichu. He gets a job at a toy company and takes a liking to his boss's daughter. Vichu does well at his job, and the other employees become jealous. Pappu meets his brother and finds out that his mother is sick with worry since he disappeared. He goes back to the scientists and asks to be changed back into a boy. He is changed back into an 8-year-old, but at night he turns back into a man. The scientist is not quite sure why or how that is happening.
Pappu spends the day living as a boy with his mother, but when night comes he resumes his life as a man. Pappu is kidnapped by one of his jealous coworkers while he is still a man. When he turns back into a child, the kidnappers thinks he has made a mistake and lets him go. Pappu ends up marrying his boss's daughter. He lives with her as a man at night and goes back to his mother as a boy during the day. His wife becomes pregnant, and she is angry for having a child from a child.
The movie ends twenty years later. Pappu really is a man at this time, and he is still married. At night he turns into a 40-year-old man. His is still taking care of his son. He is unable to get in touch with the scientist. During the day he lives as a real man, and at night he lives as an older man.