Siddharth Soundaarajan is an upcoming violinist in Chennai who stumbles upon an accident: a girl lying in a pool of blood. He rushes her to the hospital with the help of an auto driver Adaikalam and a couple, but his efforts come too late, and the girl passes away while holding his hand. Traumatized, he returns home clutching one of her slippers, and he drifts through the city in a red car, choosing to help homeless people as a way to cope with the crushing grief.
After that fateful night, Siddharth begins to notice a haunting presence in his apartment. The house seems to clean itself up even when he leaves a mess, and his bottle opener vanishes whenever he tries to drink. To confront what’s happening, he teams up with his friend Badri and they hire a psychic to perform an exorcism. The seer turns out to be a fraud, and a strange apparition drives her from the apartment in fear. Around this time, Siddharth also learns that his next‑door neighbor’s autistic son plays with an imaginary friend, a detail that adds to the eerie mood surrounding the building.
When Siddharth’s mother Janaki Soundarrajan visits, she is injured by a drunk neighbor who is abusing his wife. The next day, she experiences a freak accident in the bathroom but is saved by the same unseen presence, which seems to alert the neighbors. Disturbingly, Siddharth misreads the supernatural events as a direct threat to his mother and even threatens to kill himself so that the ghost might return as a vengeful specter. He tries numerous rituals from different faiths to drive away the spirit, yet nothing works and the haunting persists. A petty thief is also stabbed during a break‑in at Siddharth’s apartment, adding a grim, real‑world layer to the tension.
Driven by a growing belief that Bhavani’s ghost is at the root of these events, Siddharth decides to find Bhavani’s family to seek their help. He learns that Bhavani’s father runs a local ice factory, and he confronts him at his residence to show him the ghost. When his mother phones from the hospital to report that the ghost has, in fact, saved her life, Bhavani’s father begins to wonder whether the spirit is protecting Siddharth. The apparition soon appears again, and he pleads with her to come home with him, but she remains at the apartment. Siddharth comes to a painful realization: Bhavani’s spirit never meant him harm.
With this newfound understanding, Siddharth concludes that Bhavani can only rest if her killer is brought to justice. He and his friends set out to uncover the truth behind Bhavani’s death. They track down Adaikalam, who explains that he saw a green car fleeing the scene. The pursuit leads them to a shady workshop where the truth begins to unravel: Adaikalam had stolen an orphaned child from the hospital because he and his wife could not have children of their own. Adaikalam’s cousin, who was in the car that day, reveals that the actual vehicle that hit Bhavani was not green but red—much like Siddharth’s own car. Confronted with the evidence, Siddharth returns to Adaikalam and asks him to distinguish between red and green apples, a task he cannot perform due to colorblindness.
In a devastating turn, Siddharth realizes that he himself is the killer. He resolves to tell Bhavani’s father the truth, a decision that the ghost seems to oppose at first, but he presses on anyway. Overcome with guilt, Siddharth attempts suicide, and Bhavani’s spirit intervenes, cremating her own body that had been preserved by her father in ice. This act allows her to move on to the next world. Bhavani’s father consoles Siddharth, telling him that his kindness would have prevented any deliberate harm, and that love between Bhavani and Siddharth grew from a place of compassion, not malice.
