For every action, there is an equal and opposite reaction. What happens when your small action affects so many people's lives? how the butterfly effect plays an important part in all our actions forms the crux of N4.

Sakthi is a petty thief in a Chennai slum, who learns the Adimurai, the ancient and oldest form of martial arts. Meanwhile, an evil man and his son challenge Sakthi for a kickboxing tournament, and Sakthi agrees to participate in it.

A local don locks horns with the new cop, who has come to his place, but both are not what they initially seem to be.