Circle Inspector John Luther is an honest and efficient police officer stationed at the Munnar police station, whose unwavering dedication to duty often comes before everything else. His family scene opens with his sister, Leena, preparing for an engagement, while his father, Mathew, expresses quiet disappointment over John’s relentless work pace. The next morning, the tension between duty and family life continues as John slips out again soon after the ceremony ends, chasing a case that will soon pull him into a web of violence and mystery.
John is assigned to investigate a deadly motorbike crash from the previous night. The rider, Prakashan, dies on the spot, but the pillion passenger vanishes. Using CCTV footage and photos captured by bus passengers who witnessed the incident, the police pinpoint a pickup truck involved in the collision. However, the truck’s driver claims he dropped the pillion passenger on the road and knows nothing more, leaving John to chase elusive leads.
Complicating matters, a schoolboy disappears from the same area, and John struggles to find a direct link between the two cases. A crucial clue emerges when he spots a pickup truck on the crime scene that still lacks a number plate, sending the investigation into a fresh direction. As the case unfolds, John confronts two men linked to another high-profile investigation and ends up in a brutal confrontation. A blow delivered with a tube light to the left side of his head leaves him with significant injuries: complete hearing loss in one ear and only about 20% hearing in the other. The hospital gives a stark prognosis, and John returns to work after a month, now relying on a hearing aid and a voice recorder to communicate while continuing to pursue the truth.
Back in action, John tackles the case of another missing woman, Geetha, and follows a trail that leads to a house where the pickup truck was spotted. The owner, Joby, becomes a key figure, and John discovers that the driver is Venkit, a Tamil daily laborer who recently started with the family’s business. Venkit’s uncle, Prasad, retreats to his hometown in Kolukkumalai for health reasons, but John’s inquiry follows him there.
In Kolukkumalai, Prasad claims he already knew Venkit was troubled—an impression formed from a dark medical past. Venkit, a bright medical student who earned MBBS with top marks, was barred from practicing after a house-surgery incident that led to a patient’s death. This trauma drives Venkit toward a dangerous fascination with surgical acts, and Prasad warns that he has witnessed a cascade of murders. John obtains the body parts of three victims and uncovers a list of medical students who were debarred; Venkit’s name is absent, but Prasad’s name appears, revealing that Prasad is the true serial killer behind the string of crimes.
Armed with this revelation, John races back to the hospital to confront Prasad. In a desperate clash, Prasad overpowers John’s colleague, ASI Rajan, rendered unconscious, and begins a grisly surgery on him. A brutal fight ensues, leaving John gravely injured, yet he manages to kill Prasad. The battle ends with John’s full recovery over time, and the physical and emotional toll of the case lingers, shaping his approach to justice.
In the closing scenes, John finalizes the crime file and submits the closing report, while his superior informs the DGP over the phone that John is poised to be reassigned to a new case. The story closes on a note of quiet resolve, emphasizing John’s steadfast commitment to protecting others even at personal cost, and leaving the door open for the next chapter in his police career.
