Endhiran is a typical science fiction movie in which Rajinikanth plays a dual role of a scientist and a robot. The scientist Dr. Vaseegaran creates a robot with artificial intelligence and names it as Chitti. The robot eventually falls in love with Sharmili, a character played by Aishwarya Rai. The robot starts writing romantic poems and behaves like a human being.

Being aware of the extraordinary artificial intelligence of the robot, the villains try to get hold of the robot. The scientist then fights back to prevent the robot from falling prey to the enemies. The story then revolves around the battle between the scientist and the evil forces.