John Luther

John Luther returns home late after his sister Leena's engagement, earning his father's reproach. He is portrayed as a workaholic who prioritizes duty over family. This moment establishes the tension between his professional commitment and personal life.

The next day, John leads the investigation into a fatal motorbike crash from the previous night, where driver Prakashan died and the pillion rider vanished. CCTV footage and photos from bus passengers point to a pickup truck involved, but the truck's side plate is missing. Police begin tracing the unmarked vehicle and looking for clues at the crash site.

Around the same period, a schoolboy also goes missing in the same area, hinting at a possible link to the crash. John struggles to connect the two cases at first, but remains convinced there might be a connection. The investigation widens to look for patterns and suspects.

John notices a pickup truck at the crash site that lacks a number plate, making it a key suspect. The police issue a lookout for the unmarked vehicle and collect further sightings. The plate-less truck becomes a recurring clue guiding the investigation.

John confronts two goons connected to another high-profile case and ends up in a street fight. A tube light strike to his left ear leaves him seriously damaged, with total hearing loss in that ear and only 20% hearing in the right. He is hospitalized and later starts using a hearing aid and a voice recorder.

While recuperating, John takes a month's leave to adjust to his disability and refocus on the case. He adopts a hearing aid and uses a voice recorder to aid investigations. The break marks a turning point in his approach to police work as he plans to return stronger.

Returning to duty, John investigates Geetha's disappearance and follows leads to a house where neighbors had spotted the pickup truck. The case tightens around the truck and its drivers, pulling John deeper into the mystery. This investigation links earlier clues to a broader conspiracy.

Questioning the house owner Joby, John learns the truck's driver is Venkit, a recently hired Tamil daily laborer who is trying to sell the truck due to bad business. Venkit is currently in Chennai, complicating the search and widening the geographic scope of the case. The investigation shifts focus to Venkit and his associates.

John traces Venkit's connections to his uncle Prasad, a retired man living in Kolukkumalai, and travels there to question him. Prasad becomes a crucial figure whose background gradually exposes a deeper conspiracy behind the murders. The interrogation uncovers tensions and raises questions about Prasad's role.

Prasad reveals that Venkit was a psycho and a bright MBBS student who was debarred for practicing medicine during his house surgency after accidentally killing a patient. He admits to having witnessed the murders and hints at Venkit's involvement in a broader pattern of killings. The dialogue deepens the mystery and shifts suspicion toward Prasad as the killer, at least in part.

John collects body parts from the three victims and cross-checks medical student debarment lists. He discovers Prasad's name on the list and notices Venkit's name is absent, leading him to conclude that Prasad is the true serial killer behind the crimes. The discovery reframes the entire investigation.

John returns to the hospital to capture Prasad, but Prasad incapacitates ASI Rajan and begins performing surgery. A brutal fight ensues, leaving John seriously injured, but he ultimately kills Prasad to end the spree. The hospital scene marks the dramatic resolution of the case.

Recovered from his injuries, John submits the closing report of the crimes. His superior informs the DGP that John is going to be assigned to another case, signaling a transition to a new assignment. The ending reinforces John's resilience and ongoing commitment to justice.