Dhanush, Karthik, Amyra Dastur
The film begins in a fantasy sequence taking place in Madhumitha's (Amyra Dastur) imagination as she shares the story with her psychiatrist, Dr. Radhika (Lena): Munaruna (Dhanush) is a Tamil worker in Burma. His friend Saamuda (Jagan) falls in love with Mallika (Aishwarya Devan), but Mallika loves Munaruna instead. Munaruna saves Samudra (Amyra Dastur), the daughter of a Burmese army general, from a Ferris wheel accident and they fall in love. When Mallika learns about this, she is devastated and marries Saamuda. The Burmese general disapproves of the union between Munaruna and Samudra, and revokes the privileges that the Tamil immigrants had until then. Violence breaks out and the Tamil nationals flee Burma. Munaruna and Samudra also join the refugees on on a ship along with Saamuda and Mallika. When Samudra's father comes looking for her, Mallika spitefully reveals where they are hiding. As Samudra and Munaruna try to escape by diving into the ocean, Munaruna is shot and killed. Samudra drowns after promising to be together forever.
Back in Dr.Radhika's office, Madhu claims that it is the story of her previous life and she has already met Saamuda and Mallika as Jagan (Jagan) and Meera (Aishwarya Devan), who are fellow programmers in the same gaming company. Radhika dismisses this and gives Madhu medicine for stress. Madhu meets Ashwin (Dhanush) a new employee in her company. Madhu instantly realizes his resemblance to Munaruna and flirts with him relentlessly, all the while calling him irrelevant names. Kiran (Karthik) is their middle aged, fun-loving boss and he knows to extract work from employees with ease. Meanwhile, Meera hallucinates about ghosts that try to rape her and she jumps from the office window and dies. Madhu is disturbed and attends her therapy sessions with Radhika when she remembers her first birth. Madhu and Ashwin meet with a car accident and Madhu is admitted in a hospital. There, she dreams about overhearing a policeman Gopinath's conversation about Kaali and Kalyani, when she intervenes and says that she knows their whereabouts. Once awake, she recites the dream to the policemen in the hospital and they are confused. But, police commissioner Gopinath (Ashish Vidyarthi) visits her and Madhu realizes that he looks like the police from her dream. He says that the Kaali-Kalyani story was a missing person case that happened 25 years ago. Madhu claims that Kaali and Kalyani were killed and buried and takes Gopinath and Ashwin to a place where they dig up and find skeletons identified as remains of Kaali and Kalyani. Gopinath finds a ring engraved with letter R on one of the skeletons. Ashwin also happens to see this and is confused as to what R may mean.
Madhu returns to her therapy, and Kiran hears about her hallucinations and rushes to the clinic. Madhu hallucinates about her third birth, where she is Kalyani, a Brahmin girl who falls in love with a rowdy Kaali (Dhanush) and her father forcefully arranges her marriage with RaviKiran (Karthik) when Kaali is in jail for murder. Kaali escapes from prison and meets Kalyani and they plan to elope, but RaviKiran finds out and surprisingly, offers to help them. He takes them to a secluded spot where he murders Kaali and Kalyani out of jealousy and buries them. (The ring is Kalyani's engagement ring with Ravikiran's initials).
In the present, we find that Kiran is actually RaviKiran in his youth. When he finds that Madhu is a reincarnation and not a mere doppelganger, he kidnaps her and tries to kill her. Ashwin in the meantime, finds video games whose themes, surprisingly resemble the stories of Madhu's previous births. He also finds a drug that the employees have been using to boost memory. He realizes that Kiran has been giving illegal drugs all this while to boost the memories of employees so that he can profit with uniquely themed intense games. While other employees like Meera experienced hallucinations as side effects, Madhu had an extreme case of remembering her previous birth. Ashwin confronts Kiran, and in the ensuing fight, he saves Madhu and Kiran is killed. Gopinath, covers up the murder as suicide, stating that Kiran killed himself as all the illegal activities that he did in the name of Gaming has been exposed.