Late at night on a deserted road, well-known actor Armaan Kapoor (Vivan Bhatena) loses control of his car, apparently trying to avoid something, and drives into the sea. Senior Police Inspector Surjan Singh Shekhawat (Aamir Khan) with his assistant Devrath Kulkarni (Rajkummar Rao) begins an investigation. Armaan's body is retrieved from the sea and identified by his wife Sonia (Pariva Pranati). Sonia is perplexed that Armaan, a huge movie star, was driving himself (usually has his driver Ramu) and without his spot boy Yuvraj. He left film city after his shooting at 2:20 am and the accident happened at 4 am. He must have stopped somewhere in between. Also there have been many such freak accidents on that particular section of the road in the last 3 yrs. Surjan's personal life has been in turmoil ever since his 8-year-old son, Karan, recently drowned during a family outing. His wife, Roshni (Rani Mukerji) is still grieving, and Surjan has developed a guilt complex.Surjan learns that on the night of Armaan's accident, Armaan was travelling with Rs 2 million in cash, which is missing. Armaan's accountant says that Armaan had made 2 more such large cash withdrawals in the recent 2-3 yrs. One of those payments of Rs 10 Lakhs was delivered to Hotel Lido. Further investigations reveal that Armaan had given the money to a blackmailer, a pimp named Shashi (Subrat Dutta). Three years back, Shashi had performed a cover-up for Armaan and his friend Sanjay (Suhaas Ahuja). Once he learns of Armaan's death, Shashi takes off with the cash. Shashi's friend, Taimur (Nawazuddin Siddiqui), picks up Sashi's discarded SIM and begins blackmailing Sanjay (by calling in name of Sashi). Taimur learns that Sashi had demanded 50 Lakhs from Armaan and was now pestering Sanjay for the remaining 30 Lakhs. Sanjay gets Shashi murdered and Taimur knows that Sanjay ordered the hit on Sashi since he had read Sanjay's message asking Sashi to meet him at the carnival (where Sashi was killed with a rifle shot).Roshni seeks solace from a medium neighbor, Frenny Mistry (Shernaz Patel), who claims to be in touch with Karan's soul. Roshni and Surjan have recently moved into Frenny's building. Frenny meets Surjan one day and tells him that she has been waiting for him. She says his son Karan wants to speak to him. Surjan is livid at this suggestion. Roshni wants to entertain the possibility, but Surjan won't believe in this nonsense. Roshni has sessions with Frenny without Surjan's knowledge. One night, Surjan is propositioned by an escort, Rosie (Kareena Kapoor). He declines but asks if she can become an informer as her clues prove to be most helpful in the investigation. The police find Shashi's body, along with the blackmail money and a DVD. The DVD contains embarrassing CCTV footage of Armaan and his friends leaving a hotel with a girl. Rosie confides in Surjan that three years ago, she was picked up by Armaan and his friends, Sanjay and Nikhil, but reveals nothing more. Surjan discovers that Nikhil has been brain-dead after the incident three years ago. Surjan finds that Roshni has been having seance sessions with Frenny and is livid. He interrupts on of the sessions and pulls Roshni away. Roshni tells Surjan that Karan wants to talk to him and that "talking to him" gives her satisfaction in life. Roshni leaves Surjan.Sanjay gets Taimur killed next (Taimur had called Sanjay for a meeting at a railway station to deliver the money, but Sanjay set his goons on Taimur, after handing him the money. But before being killed Taimur had handed the money bag to his squeeze Nirmala (Sheeba Chaddha) who is also a prostitute). The police learn he is behind Shashi and Taimur's murders (One of the goons died during their escape and through his phone the police track Sanjay) and Surjan arrests Sanjay. Sanjay confesses that three years ago, he, Armaan, and Nikhil had picked up an escort to celebrate Nikhil's birthday. Nikhil began making out with the girl in the backseat. The car door opened by accident, throwing both Nikhil and the girl from the moving car to the road. Armaan and Sanjay rushed Nikhil to the hospital but fearing scandal, left the girl on the road. Sanjay had called Shashi to take care of her. Shashi informed them that the girl had died and that he had footage of the three leaving with her. Since then, Shashi had continued to blackmail them for money. Surjan re-watches the footage and realizes that the girl is Rosie.As he drives Sanjay to the police station, they approach the same road where Armaan had his car accident. Both men see Rosie standing ahead. In a re-enactment of Armaan's accident, they swerve the car to avoid a collision with her and it falls into the sea. With Sanjay already dead, Surjan struggles to get out of the car. Rosie saves him. Surjan's superior advises him against reporting the incredible story and Surjan writes in the official report that Armaan's death was an accident. He returns to the riverside place where he used to meet Rosie and uncovers her remains where Shashi had hidden her body. Remembering that he had been told that "the dead come to those who are troubled," he gives her a proper funeral.Now more accepting of the supernatural, Surjan finds a letter from Karan, penned by the medium. Through the letter, Karan tells Surjan not to blame himself for his death and that he wants both his parents to be happy. Surjan cries and reconciles with his wife. In a post-credits scene, two workers are seen putting a caution sign-board on the same accident spot.