Kannai Nambathe

Years ago, a woman runs an NGO caring for orphans. Her daughter grows jealous of the attention the orphans receive and poisons their food, killing one and injuring several. When the mother discovers the plot, she confronts her daughter, who fatally strikes her with an iron rod. The daughter is arrested by the police.

In the present day, Arun and his friend Jagan search for a rental after being kicked out by a landlord who discovers his relationship with Divya. They finally find an apartment that Arun must share with a roommate named Somu. Arun moves in, and Somu invites them to celebrate with a drink.

Arun helps Kavitha after she nearly crashes and asks him to drive her home. He agrees and drops her off, and she offers him permission to keep using her car until the rain stops. He then returns to the restaurant to fetch his friends.

On the way back, Arun tells his friends about Kavitha and the ride. Somu makes a disturbing remark about a woman staying alone at night, joking about the odds of trouble. Arun dismisses the idea as harmless.

Somu, high on drugs, steals Kavitha's car key from Arun and drives to her house to satisfy his urge. He confronts Kavitha, but she resists. In the struggle, Somu accidentally kills her and escapes.

The next day, Arun wakes up and finds Kavitha's body in the car trunk. He calls Somu for help; Somu discourages calling the police, arguing the story lacks proof. Remembering CCTV outside Kavitha's house, Arun resolves to retrieve evidence and buys a CCTV jammer to hide his entry. The seller also assigns a follower to tail them.

At Kavitha's house, Arun tries to retrieve CCTV footage but the hard drive has been removed by an unknown person. Somu, who fears dogs, is outside and is attacked by a dog, then drives away and accidentally hits a man on the road. Aparna explains that the man was the police officer's son who had been stalking her, and Somu's intervention saves her. They decide to keep quiet to avoid trouble.

Arun and Somu decide to dispose of the two dead bodies by dropping them off a viaduct onto moving cars, creating the appearance of an accident. Kavitha's body goes missing from the trunk, and they learn the dead man's police father is Divya's uncle.

News outlets report Kavitha's death, and Arun and Somu receive a video revealing they dumped the bodies. A blackmailer demands 3 million rupees and threatens to go to the police if they refuse. They scramble to find clues to locate the blackmailer.

They identify Ilamaran, the CEO of a pharmacy company, as the man behind the unknown blackmailer. They send him the CCTV footage and use the information to extract a ransom, planning to use the money to pay the other blackmailer. Ilamaran reveals that he later placed Kavitha's body back in Arun and Somu's car and returned it to its original location; his henchman Simon then steals the ransom money and escapes.

During the meetup, the blackmailer Vasundhara, also known as Vasu and revealed to be Somu's girlfriend, confirms Somu killed Kavitha and dumped her body in Kavitha's car trunk. Somu tries to recruit the CCTV jammer shop contact to join their blackmail against Arun. They attempt to kill Arun but fail and escape.

Arun calls Divya to tell her the whole story and asks her to inform her uncle for help. He then follows Ilamaran to track down Somu and Vasu. To his shock, Kavitha is alive and running a trafficking operation with Ilamaran; Arun records video evidence and confronts them, while Kavitha confesses.

Somu and Vasu arrive at the confrontation scene and a fight breaks out; Arun is beaten and nearly killed. Divya's uncle arrives and shoots Somu, killing him and Vasu; Divya's uncle is injured in the process. Savitha and Ilamaran escape, leading to a car chase that ends in a crash and an explosion.

In the aftermath, it is revealed that Savitha and Ilamaran's car did not explode by accident but was set alight by Arun to ensure they could not survive and be protected by the health minister.