Shakti (Madhavan), a villager, comes to Chennai and joins his uncle Kirikalam (Vadivelu), whose stall of magic tricks at an exhibition brings poor collections.

The next-door stall is an all-girls stand, with mermaid costumes; Velli (Reema Sen) is the 'head mermaid'. Shakti and Velli fight regularly; Shakti feels Velli's team is luring their customers away; Velli thinks Shakti is an unsavoury character. Yes, love has been brewing as an undercurrent between these two...

Manivannan, the owner of the exhibition grounds, keeps harassing Velli, has his eyes set on her and abducts her. But Shakti rescues Velli. Velli's betrothed suitor tries to force her to be with him; again, Shakti steps in to save and protect Velli.

A series of murders occur in different towns and 2 perpetrators slink away from each. At one crime scene, a witness spots the main culprit. The police instruct him to sketch the murderer. Police investigate a horrendous fire in Kumbakonam; the investigating officer (Bhagyaraj) sees the pictures of the deceased and finds Kannan's (Madhavan – Version 2) picture, which resembles the perpetrators of the series of arson incidents. Kannan is exactly like Shakti, only he has light eyes...

Shakti is spotted, recognized and arrested. Kannan follows the murder investigation, meets Kirikalam and Velli and plots to help Shakti get out. Shakti and he escape by the skin of their teeth. What led Kannan to murder all those people? Flashback time…

Kannan, his elder brother and father are caterers, commissioned to cook for a marriage function in Kumbakonam. Kannan meets Jyoti (Anushka), falls in love and she reciprocates. The groom creates trouble at the wedding and walks out; Kannan suggests that his elder brother marry the bride left in the lurch. All accept this brilliant suggestion, but a raging fire attacks the marriage house. (This is the revenge of a gang of goondas against the bride's father, because he opposed their takeover and sale of a large parcel of government land.) All are killed in the fire, except Kannan and his friend. Kannan's eyes are damaged by the fire, hence the light colour and poor eyesight. He vows retribution on the villains and sets about cold-bloodedly deleting them.

How Shakti helps Kannan get his revenge forms the rest of the story. This second half is full of fast-paced action; the end is both feel-good and poignant.

Madhavan's skills in this movie prove his talents. He has done both roles well and differently as unique individuals. Shakti is a fun-loving, full-of-life young man; Kannan USED to be a happy and contented young man; after his personal tragedy, he became a serious loveless vigilante.

The first half is filled with comedy; the wedding function events are so colourful, happy and filled with song and dance; the action scenes display how good Madhavan is in a fight. Reema Sen is very pretty with her pouty indignation and quick. Anushka is surprisingly good and very attractive and shows she is a promising actress.

Sundar C. has once again proved his mettle at combining a good story with good entertainment value in this comedy-romance-action film. Rendu is a good entertainer, a commercial film with enough twists in the tale of 2 look-alikes to be different enough.