The film starts with the murder of a former Police Commissioner, Shanmuga Sundaram (Subbu Panchu) by an escaped prisoner Kamal Ekambaram (Riyaz Khan). The story then shifts to Masilamani aka Massu (Suriya) and his friend Jet Li aka Jettu (Premgi Amaren) who are small-time con artists. Massu meets Manini (Nayantara), a nurse and they subsequently fall in love. While trying to escape after a heist gone wrong, Massu and Jet meet with a car accident, post which Massu starts seeing dead people, with whom he can communicate. Jettu had died in the accident and is now a ghost, too. Massu forms a group of loitering ghosts to earn money by performing fake exorcisms and extorting money from scared rich people, while promising the ghosts that he would fulfill their last wishes in return. Meanwhile, Manini who thought Massu was working in a finance company gets to know about the fake exorcisms and leaves him in a heist.
One day he meets a ghost called Shakthi (also Suriya), a Sri Lankan Tamil and look-alike of Massu. Shakthi initially seems to help Massu to pull off a large heist. However, he wants to use Massu for his own needs. He sabotages the plan and tricks Massu into running over Anthony (Sharath Lohitashwa), a hawala broker. Corrupt Assistant Commissioner of Police (ACP), Vikram Lakshman (Parthiban) takes charge to investigate the case and finds out that Massu is, somehow involved in the murder. Meanwhile, the ghosts start striking against Massu as they assume that he would cheat them. Massu yells at them and orders them to go out. Just then, Shakti arrives as the ghosts have called him. The ghosts go with Shakthi. But Jettu manages to convince Massu and he agrees to fulfill the wishes of the ghosts. He starts fulfilling the wishes of all the ghosts. He first fulfills the wish of the ghost of a woman, Padma which is to see her son, who is actually blind. Massu is frustrated to learn that he is accidentally responsible for the death of Padma. As a sort of seeking forgiveness, he guides her son, takes care of him and gets his eye operated upon. Her wish fulfilled, Padma attains salvation. This incident moves Massu and he fulfills the wish of every ghost. Meanwhile, Shakthi manages to use Massu to kill another person, Madhivadhanan aka Madhi, an MLA and associate of Anthony. While Massu is furious with Shakthi for having made him a double murderer, Kamal meets Massu and starts telling him Shakthi’s past: Massu is Shakthi’s son.
Shakthi was a police officer in Quebec City, Canada. He got married to Anuradha aka Anu (Pranitha Subhash), who is a teacher of his daughter Megha’s school, just for Megha’s wish. Shakthi secretly learns that Anu really loves and takes care of Megha. Anu & Shakthi fall in love. Anu gives birth to a son. Anu owned land in India, which she wanted to donate to an orphanage so that a new orphanage could be built there. Kamal was the only friend of Anu in India and agreed to help with the registration. Sakthi and Anu, along with their little daughter Megha (Yuvina Parthavi) and infant Massu, came to India to complete the registration but get to know that industrialists Radha Krishnan (Samuthirakani) and Anthony forged documents and planned to take the land away to construct flats there. Since Shakthi remained undeterred and did not give way, Radha Krishnan, Anthony and their henchman Madhi and Shanmuga Sundaram, killed Shakthi, Anu and Megha and pinned the murders on Kamal. Massu had escaped because Megha had left him safe in a small house with a family nearby.
Shakthi through Massu wanted to kill all the people who were responsible for his family’s demise. Knowing the truth, Massu decides to kill the last person, Radha Krishnan, himself. Radha Krishnan also knows who Massu is and tries to kill him but Kamal saves Massu. However, because he was hit on the head by Radha Krishnan, he loses the ability to see and converse with the spirits anymore. With the help of Vikram, who double-crossed Radha Krishnan, Massu finally kills Radha Krishnan. As Shakthi’s last wish is fulfilled, he goes to heaven and joins with Anu and Megha. Manini now reunites with Massu and they get married as Jettu remains with Massu forever.