Naan Sigappu Manithan

Indhiran suffers from narcolepsy, a rare disorder that causes him to fall asleep whenever his emotions reach an extreme level. When Meera's car is hit by another vehicle on the under-construction bridge, the shock triggers his condition. While asleep, he can still hear everything happening around him, which is why he hears the entire assault but cannot physically respond. He only manages to shed a tear, helpless to save Meera.

Earlier in the film, Indhiran nearly gets hit by a vehicle and fear immediately triggers a sudden sleep episode.

Indhiran discovers that loud sudden sounds trigger his sleep, so he buys a portable audio player to block out external sounds. A transformer explosion has no effect on him because of the music playing at full volume. He also consults a meditation teacher who teaches him to stay calm and anticipate shocks in advance. He practices standing between loud trains with music playing and eventually gains enough control to stay awake through his revenge mission.

Indhiran realizes he had never fallen asleep while taking a shower, showing his condition can be managed in certain states.

Karuna orchestrated the attack on Meera as revenge for his wife Kavitha's death. When Indhiran discovered Kavitha's affair with Aravind and told Aravind the truth, it triggered a chain of events that led to Kavitha's accidental death and Aravind's murder by Karuna. Believing Indhiran was responsible for Kavitha's death, Karuna wanted him to suffer the same way by having his loved one attacked.

The timeline shows Karuna and Kavitha celebrating their success after manipulating Aravind, just before Indhiran drops by unexpectedly.

The attack on Meera was directly caused by the events surrounding Kavitha's death. Karuna used his wife to manipulate Aravind into funding his US immigration plans. When Indhiran exposed the affair to Aravind, Aravind confronted Kavitha and accidentally killed her during a physical altercation. Karuna then killed Aravind and arranged for the bodies to be disposed of by thugs. Karuna blamed Indhiran for this chain of events and arranged the brutal attack on Meera as retaliation.

Indhiran advises Kavitha against the affair, not knowing this conversation will lead to his own tragedy.

Sathish kills Sekhar to prevent him from revealing the truth about who hired the thugs. When Indhiran tracks the red car to a workshop and confronts Sekhar, the mechanic tries to flee. Sathish arrives at the scene and kills Sekhar, then injures himself to make Indhiran believe Sekhar attacked him and escaped. This cover-up protects Karuna, who had ordered the attack on Meera.

The timeline establishes that Sathish and Karuna are Indhiran's friends who accompanied him to buy the gun, creating opportunity for this betrayal.

The final scene shows Indhiran hugging Meera, who is tearful while hearing him, indicating she is recovering from her coma. After completing his revenge, Indhiran's new wish is to help Meera recover soon. While the movie does not show a complete recovery, the ending suggests hope that she will heal with his support.

The entire revenge plot is driven by Indhiran's vow to get justice for Meera and help her recover.

Karuna kills Aravind after Aravind discovers he has been manipulated. Kavitha had convinced Aravind to finance Karuna's US immigration by promising they could be together once Karuna left. When Aravind confronts the couple and realizes he has been cheated out of money, he strikes Kavitha in rage, causing her to die when her head hits a cupboard corner. In retaliation, Karuna kills Aravind and arranges for the thugs to dispose of both bodies.

Karuna was using his wife to manipulate Aravind for his business ambitions from the start.

Indhiran uses his newfound control over narcolepsy to investigate systematically. A sympathetic police officer provides him with information about attack cases. Indhiran recalls one of the thugs' name (Sekhar) and his ringtone. The police also discover the criminals drove a red car. Indhiran traces the red car to a petrol bunk, where the driver reveals it was with a mechanic named Sekhar. Following this lead takes him to the workshop where the confrontation occurs.

Indhiran remembers the ringtone of one of the attackers while the police find the red car clue.

The thugs beat Karuna because they discover he was the one who killed Sekhar. Earlier, Karuna had asked the thugs to bring Indhiran to the same location where Sekhar was killed. The thugs realize Karuna set them up and killed their associate, so they attack him. Later, when Indhiran removes Karuna's audio player and he gets an adrenaline rush, he falls asleep, allowing the thugs to attack him until a water pump wakes him.

The thugs had helped Karuna dispose of bodies earlier, creating a dangerous alliance built on mutual secrets.

Meera becomes pregnant after she and Indhiran have sex in his swimming pool, fulfilling one of his dreams. However, after the brutal attack on the under-construction bridge, Meera falls into a coma and the child is aborted as a result of the assault. This loss adds to Indhiran's determination to seek revenge for what was done to Meera.

Meera urgers Indhiran to find a way to stay awake so her father would accept him, leading to the pool scene.

Indhiran kills Karuna after learning the truth behind Meera's attack. Although they were close friends, Karuna had orchestrated the assault on Meera as revenge for Kavitha's death, which he blamed on Indhiran. During their confrontation, Karuna attacks Indhiran violently. Despite feeling bad for his friend and hesitating due to their close bond, Indhiran remembers Meera's suffering and kills Karuna by kicking him into a steel bar, ending the friendship forever.

Karuna had planned to make Indhiran suffer the same way he did by having Meera attacked.

Meera's father Jayaprakash opposes the marriage because of Indhiran's narcolepsy condition, specifically his inability to stay awake during sex. He believes Indhiran cannot fulfill his duties as a husband. Meera encourages Indhiran to find a way to overcome his condition, leading to their discovery that he can stay awake during a shower and their subsequent intimate encounter in the swimming pool.

This opposition drives the plot forward as Meera and Indhiran seek ways to prove his capability.