Ghajini

Chitra, a medical student researching the brain, begins a covert investigation into the alleged anterograde amnesia of Sanjay Ramaswamy. Her professor refuses access to Sanjay's records, so she resolves to uncover the truth on her own. Her curiosity pulls her into a shadowy pursuit across Chennai.

Sanjay experiences memory resets every 15 minutes and relies on a system of photographs, notes, and tattoos to reconstruct his life after each cycle. This routine keeps his past fragmented and his current actions difficult for others to track. The memory cycle drives the tension as characters try to understand his behavior.

Sanjay's actions reveal a deadly motive: he is avenging Kalpana's death and targets those involved. His primary focus becomes Lakshman, a Kolkata-based trafficking kingpin with influence in Chennai. Inspector Ravi begins chasing the serial murders linked to Sanjay.

Ravi corners Sanjay at his flat, knocks him unconscious, and discovers two diaries labeled 2002 and 2003. The diaries chronicle Sanjay's life, loves, and plans for Kalpana's murder and Lakshman's downfall. The discovery confirms Sanjay's meticulous, years long record of his actions.

The 2002 diary recounts Sanjay meeting Kalpana, a struggling model, while posing as Sanjay Manohar. They fall for each other, sharing a growing affection under the false identity. The diary ends with Sanjay proposing and hinting that he will reveal his true name if she accepts.

Sanjay tracks Lakshman to a college function, photographs him, and plans to kill him. In the chaotic parking lot, he inadvertently kills one of Lakshman's goons instead of Lakshman. Lakshman remains unaware of Sanjay's presence and the hidden threat.

Chitra visits Sanjay's flat, finds Ravi beaten and bound, and uncovers the two diaries. She frees Ravi and learns that Lakshman is Sanjay's intended target. Realizing the danger, she warns Lakshman that Sanjay is coming for him.

Believing Lakshman is in danger, Chitra informs him; Sanjay arrives at their location with no memory of the prior events and a new pursuit begins. Ravi regains consciousness but is struck by a bus, dying on the street, while Chitra escapes to a phone booth. The city becomes a tangled chase as memory and vendetta collide.

Chitra's warning triggers Lakshman to take precautions; Sanjay goes to Chitra's dormitory to kill her. Chitra calls the police and Sanjay is arrested, ending the immediate threat to Lakshman for the moment. Lakshman, watching the investigation, realizes the true scale of Sanjay's vendetta.

Lakshman and Ram arrive at Sanjay's flat, destroying photographs, notes, and tattoos to erase evidence. Chitra reads the 2003 diary, which reveals Kalpana's past commitments and hints at her trafficking rescue mission. The diary deepens the mystery and fuels the pursuit.

Kalpana had traveled to Mumbai to rescue 25 Tamil girls trafficked to Mumbai and Kolkata. Lakshman kills Kalpana with an iron rod after learning of her actions. Sanjay, learning of Kalpana's death, redoubles his vow for vengeance.

In the climactic showdown at Lakshman's factory, Sanjay battles Lakshman and Ram and, remembering Kalpana's death, overpowers and kills the brothers. He leaves with Chitra, and a closing street crossing shows him smiling at a passing child as they walk away.