Ghajini () is a 2008 Indian Hindi-language psychological action thriller film directed by A. R. Murugadoss (in his Hindi film debut) from a screenplay by Murugadoss and Aamir Khan. A remake of Murugadoss' 2005 Tamil film of the same name, it stars Khan, Asin, Jiah Khan and Pradeep Rawat. In the film, Sanjay Singhania (Khan) seeks violent revenge for an attack which killed his fiancée and caused his anterograde amnesia.

Initially titled as Kajri, the core plot of the film was inspired from Memento and Happy Go Lovely. The first half was inspired by the 1969 film Sajan and the 1983 film Pasand Apni Apni, and Khan and Murugadoss co-wrote the remake, with Khan suggesting changes to suit the taste of the Hindi cinema audience. Allu Aravind, Madhu Mantena and Tagore Madhu jointly acted as the producers, while the film was distributed by Geetha Arts. A. R. Rahman composed the soundtrack and musical score, while cinematography and editing were handled by Ravi K. Chandran and Anthony. The film marks Asin's Hindi film debut, reprising her role from the original film.

Ghajini was theatrically released on 25 December 2008, coinciding with Christmas, where it became the highest-grossing Indian film of the year and the first Bollywood film to cross the 100 crore mark domestically, creating the 100 Crore Club. Ghajini'''s paid preview collections were 2.7crore. It went on to become the highest-grossing Indian film of all time until it was surpassed by 3 Idiots. Khan's character was featured in a 3D video game titled Ghajini – The Game, which is based on the film.

Plot

Sunita, a medical student, is investigating the anterograde amnesia case of Sanjay Singhania, the chairman of Air Voice, an infamous telecommunications company. Sunita does her investigation against her professor's wishes as Sanjay is under criminal investigation. Sanjay, who loses his memory every 15 minutes, uses a system of photographs, notes, and tattoos on his body to recover his memory and remember his mission of avenging the murder of his fiancée Kalpana Shetty, who was killed by Ghajini Dharmatma, a kingpin and a notable socialite in Mumbai.

Inspector Arjun Yadav investigates a recent murder committed by Sanjay of one of Ghajini's men at his house. He tracks Sanjay to his apartment and knocks him unconscious. While searching his apartment, he finds a diary in his drawer and begins to read it. Arjun learns that Sanjay, a successful entrepreneur and second generation businessman, met Kalpana, a struggling model after planning to install an advertising billboard for his company above her apartment. When his agents approach Kalpana about it, her boss misinterprets it as a romantic advance and encourages her to accept it. Kalpana decides to pose as Sanjay's girlfriend, after seeing that the false story elevates her influence at work. After learning about the rumor from local tabloids, Sanjay angrily plans to confront Kalpana. On the drive to her workplace, Sanjay witnesses a young woman help a bunch of disabled school girls cross a ditch to enter a museum, and he is deeply moved by her kindness. When he finally arrives at the ad company, he discovers that this kind-hearted woman is Kalpana. Her cheerful personality and humor capture his attention, and he decides to keep his identity a secret. Posing as a struggling model named Sachin Chauhan, he spends time with Kalpana as an ordinary man, and the two fall deeply in love. The diary ends with Sanjay proposing to Kalpana on New Year's Eve, with him deciding to reveal his true identity if she accepts, but to walk away as Sachin if she doesn't.

In the present, Arjun tries to interrogate an unconscious Sanjay about the events after the first diary to no avail. After searching his drawers again, he finds a second diary. As soon as he starts reading it, Sanjay suddenly regains consciousness, breaks free of his holds in a fit of rage and viciously attacks Arjun, tying him up and locking him in a cupboard. He later tracks down Ghajini to Sunita's college function where Ghajini is the guest of honor as the CEO of GD Pharmaceuticals, a major donor of the college. Sanjay takes pictures of Ghajini as part of his plan to kill him. In a fit of memory loss, Sanjay mistakenly kills one of Ghajini's goons, and flees the scene when he realizes that he killed the wrong man. Ghajini is perplexed and fails to understand why this mysterious killer is targeting him. He decides to find and kill his enemies from two years ago one by one, but Sanjay is not among them.

Meanwhile, Sunita goes to meet Sanjay at his apartment after initially meeting him at her college. After realizing that the door is unlocked and there is no one in the apartment, she begins searching through Sanjay's belongings and finds photographs of the people he had murdered along with a photograph of Ghajini he took at the college function as well as the two diaries that Arjun found earlier. She also finds Arjun tied up and beaten, and learns of Sanjay's murder plot. Arjun warns her to get out of the apartment quickly, but Sanjay suddenly arrives and questions who they are. Arjun quickly makes a run out of the apartment and Sanjay begins to follow him with Sunita following the two men. Arjun is hit by a bus and killed instantly. Sunita makes her escape by distracting Sanjay into a fight with some local thugs in a mall.

Sunita visits Ghajini while he is contemplating about the mysterious killer, provides him with the photos of the men Sanjay had murdered along with his identity and informs him that Sanjay is coming after him. Back in her hostel, Sunita realizes that Sanjay has a photo of her which she had him take during their first meeting so that he could remember her. When Sunita calls Ghajini to recover the photo, she inadvertently speaks to Sanjay who had broken into Ghajini's house. Sanjay asks for her address, arrives at her dormitory and attacks her. Sunita traps him in the lift and the police arrests Sanjay, sedates him to keep him under control. As the police try to figure out about the identity of the man they have arrested, they decide to call the phone numbers tattooed on his body. One of the number is Ghajini's, who visits the police station and poses as Sanjay's friend learning about the circumstances of his capture. Shortly after, Sanjay's employees and doctor arrive at the police station and take him home. After they leave, Ghajini breaks into Sanjay's apartment with his men and decides to take advantage of his condition, destroying his pictures, notes and equipment and cover his tattoos so he doesn't remember anything about the past, instead of killing him as it would complicate matters with the police.

Back at her dormitory, a shaken Sunita remembers the diaries she took from Sanjay's apartment. She reads both diaries and learns about Sanjay's background and about Kalpana. In the second diary, Kalpana accepts the proposal on the condition that she will marry only after purchasing three Ambassador cars, as her father owned his own travel company as well as three Ambassador cars before he got scammed by his brother-in-law. Sanjay gifts Kalpana an apartment via his manager, making her think that she won it in a lucky draw. Meanwhile, Kalpana buys one Ambassador car after selling some jewelry she had saved for her marriage.

To celebrate "winning" the apartment, Kalpana imprints her and Sanjay's foot impressions on a cement pad to store it as a memoir of their first step in her new apartment. Still keeping up his facade, Sanjay lies to Kalpana that he has to urgently go to his village to see his ailing mother; he actually has to go on a business trip to UK for ten days. Moments before he departs for the UK, Kalpana calls him late at night, and gives him money for his mother's treatment, having sold the car she wanted so much. This grand, unexpected display of thoughtfulness and considerate altruism leaves Sanjay shocked and sober, cementing his love for Kalpana. The second diary ends at this point. Perplexed, Sunita sets out with her friend to find the remaining pieces of Sanjay and Kalpana's story.

After some research, Sunita eventually learns that Kalpana travelled to Goa by train for an ad shoot. In the train, with the help of some soldiers, she stumbled across and freed a group of girls from a sex and organ trafficking ring organized by ruthless thug Ghajini Dharmatma. The story of the rescue of the girls makes the news and triggers a nationwide hunt by the police who start to dismantle the operations. On the train ride back to Mumbai with the girls, Sanjay calls her to check up on her and she tells him about the experience. Relieved that she is fine, he admits that he admires her kindness and bravery. He lightly alludes to his secret without giving anything away but promises to reveal more when he comes back.

Back in Mumbai, Kalpana is informed by a female constable at the police hospital that two of the twenty five girls she has brought in for treatment went missing. Perplexed, Kalpana travels to the police hospital and confronts the guard about the two missing girls. As they are arguing, Ghajini arrives with his men and confesses to Kalpana about killing the missing girls because they named him to the police. Kalpana, accusing him of being part of the system which makes society unsafe for women, leaves in disgust. An enraged Ghajini plans to kill Kalpana. Later that night when Kalpana returns to her apartment, the same constable calls Kalpana and warns her that Ghajini has set out to kill her and his henchmen are hiding inside her apartment. She advises Kalpana not to go home but it's too late. Ghajini's goons look for her while she hid inside a cupboard. That same night, Sanjay arrives from London to meet her. He rings the door bell and knocks but leaves after getting no answer. A petrified Kalpana calls Sanjay but he has forgotten his phone in his car. When Sanjay discovers Kalpana's missed calls, he calls her back but the ringtone gives away her location to Ghajini's goons. As Sanjay rushes back to her apartment, he finds Kalpana stabbed by the goons. As he is tending to her, Ghajini arrives from behind and hits Sanjay in the head with an iron rod before killing Kalpana with the same rod in front of him. He then knocks Sanjay out with another shot to the head, which results in his brain injury.

Sunita, now aware of the shocking truth, locates Sanjay in a hospital and tells him about his past, reminding him of Kalpana's murder and giving him his diaries to read. He flies into a furious and heartbroken rage. He demands to speak to Ghajini and talks to him through Sunita's cellphone, telling him that he is coming for him. Sunita helps him track Ghajini to his company. However, they find that he is already leaving the premises. They tail his car to a slum area and Sanjay, after identifying Ghajini with the help of Sunita, immediately goes after him, killing his men who get in his way. Eventually, he finds Ghajini and begins to viciously attack him but he manages to escape. Sanjay has a memory loss fit while searching for Ghajini. Ghajini takes advantage of the situation and stabs Sanjay with an iron rod. He knocks Sunita unconscious and taunts Sanjay with the grisly tale of how he murdered Kalpana. As Ghajini is about to make Sanjay relive the experience by preparing to kill Sunita in the same way with an iron rod, Sanjay recovers the memory of Kalpana and fights back, with an anger fueled strength. He kills Ghajini with an iron rod, in the same way that he killed Kalpana, thus finally avenging her murder. He breaks down as Sunita consoles him.