Rani Mehra (Kangana Ranaut) is an under-confident young woman from Delhi. Two days prior to her wedding, her fiancé Vijay (Rajkummar Rao) tells her that he no longer wishes to marry her. He explains that his lifestyle has changed after living abroad, and her conservative habits would be a wrong match for him. Stunned at the development, Rani shuts herself in her room for a day. Wanting to take control of the situation, she asks for her parents permission to go alone on her pre-booked honeymoon to Paris and Amsterdam. After initially hesitating, her parents agree, thinking that a vacation might cheer her up.

In Paris, Rani meets Vijayalakshmi, who also calls herself Vijay (Lisa Haydon), a free-spirited woman of French-Spanish-Indian descent, who works at the hotel in which Rani stays. Overwhelmed by the new city and having gotten into trouble twice - once with the local police and once with a robber - Rani intends to return to India. However, Vijayalakshmi helps her out and gives her a tour around the city. The two have a series of adventures, during which Rani relives the memories of Vijay patronising her and forbidding her from dancing and drinking - which she's free to do in Paris. During one particular incident, Rani tries on what she considers to be a revealing outfit and accidentally sends a selfie of her wearing the outfit to Vijay instead of Vijayalakshmi. She quickly realises her mistake, but unbeknownst to her, the selfie prompts Vijay to begin searching for her.

Eventually, the time comes for her to bid an emotional farewell to Vijayalakshmi and board the train for Amsterdam. However, when she arrives in Amsterdam, she finds to her horror that her hostel room is being shared with three guys: Taka from Japan, Tim from France and Oleksander from Russia. Despite being skeptical of the boys, she soon becomes good friends with them, and spends time shopping, sight seeing, visiting a sex shop, and meeting pole dancers in a club. At the club, Rani befriends a pole dancer, Roxette.

Rani slowly begins to gain confidence by taking control of her decisions. She also realises her cooking potential by winning a cook-off by selling gol gappas (an Indian street snack). She learns more about her friends' backgrounds and begins to understand how different life can be for people in other parts of the world. One day, the four find Vijay waiting for Rani in front of the hostel. Vijay apologizes to Rani and asks her to reconsider the relationship. Their conversation escalates as he tries to grab hold of Rani, but her friends retaliate, and she tells him to leave. The two meet up the next day to discuss the future, but Rani leaves abruptly, saying that she would rather speak to him after she returns to Delhi. She then meets up with her friends one last time at a rock concert she had previously chosen not to attend. After bidding an emotional farewell to them, Rani returns to India.

Back in Delhi, Rani visits Vijay at his home. Vijay thinks that she has decided to forgive him. Instead, Rani hands him her engagement ring and after saying "thank you", she walks away with a smile on her face.

Ishaan "Ish" Bhatt (Sushant Singh Rajput) is an ex district level cricketer who is a victim of politics in the cricketing selection fraternity, Omkar "Omi" Shastri (Amit Sadh) is the nephew of a Hindu politician (Bittu) who funds their business and Govind "Govi" Patel (Rajkumar Rao) is a geek who is the mastermind behind starting a sports shop which also doubles as a sports academy. Together they open a sports shop and an academy to train and promote talented budding cricketers. After toiling hard, they succeed in establishing it as a center for cricket among the local youth and start to incur profits.

Ishaan requests Govind to teach his sister Vidya (Amrita Puri) mathematics as her exams are coming up. Govind is reluctant at first but agrees eventually. Vidya and Govind gradually fall in love with each other and secretly enter a relationship unknowingly. Omi discovers the same and warns Govind of the consequences, as Ishaan is very protective of his sister.

The three friends spot a budding cricketing talent in a local boy, Ali (Digvijay Deshmukh),who has a rare talent, and Ishaan starts training him vigorously. Govind is ambitious and wants to expand the budding business by opening a shop in a mall being constructed in Navrangpura, an upcoming part of the city. With financial help coming from Omi's maternal uncle, Bittu (Manav Kaul), the trio secure the deal and set up shop in the mall. But the trouble comes when a destructive earthquake hits Gujarat and Govind's shop in the mall is destroyed. Govind is shattered as the amount of money he invested was very large and he is now loaded with a huge debt. Omi is reluctantly forced to work for his maternal Uncle's right-wing party due to the money they owe him.

When relief camps of Omi' uncles' party declines to give Muslims shelter in troubled times, Ishaan and Omi quarrel over their politico-religious outlook and temporarily break off their friendship. They again reunite after India's surprise win in the test match against Australia. Omi gets busy with religious politics and joins Bittu's party. Ishaan and Govind, meanwhile, are busy with Ali and Vidya respectively. Tension arises in the political sphere when Bittu loses the elections in his constituency to his opponent (Asif Basra) belonging to the secular party. As a part of their campaigning, Bittu sends pilgrims (kar sevaks) to Ayodhya to the Ram Temple. Omi's parents were also among them. On the returning day, the shocking news of the Godhra train massacre reaches the people. Omi is shattered but Bittu convinces him to take revenge on the murderers of his parents.

Ishaan and Govind hide Ali in Ali's house, afraid of the communal riots which were about to start. As expected, the violence starts by sunset, and the mob led by Bittu storms into the Muslim locality, killing each and every Muslim in sight. A fight ensues between Ali's father and Bittu. Ali's father stabs Bittu in defense and rushes to save Ali and take shelter in their attic. Omi, enraged at the death of his uncle Bittu, follows him with a gun. Meanwhile, Ishaan comes to know about Vidya and Govind's relationship, when he reads Vidya's text message in Govind's mobile phone about her periods. Enraged, he starts thrashing Govind while Omi enters the premises with a gun in hand, desperate to find and kill Ali and his father. Ishaan and Govind break their own fighting and try to stop Omi as he desperately searches for Ali and his father. Omi finally aims and shoots at Ali. Ishaan in a bid to save Ali takes the bullet himself and consequently dies.

The film then goes back to where it started, with Omi being released from prison ten years later. Govind and Vidya are married and have a son, whom they have named Ishaan (Ishaan Bhagat, Chetan Bhagat's son) after the late Ishaan. The film ends with a now grown up Ali debuting for the Indian cricket team against Australia. He plays his first shot by hitting the ball to the boundary with a Cover drive just like his "Ishaan bhaiya" had taught him.

Late at night on a deserted road, well-known actor Armaan Kapoor (Vivan Bhatena) loses control of his car for no evident reason, apparently trying to avoid something, and drives into the sea. Inspector Surjan Shekhawat (Aamir Khan) with his assistant Devrath Kulkarni (Rajkummar Rao) begins an investigation into Armaan's death. Surjan's personal life is in turmoil since his 8-year-old son, Karan, drowned recently 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 2 million rupees in cash, which is missing from the car. 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 Kejriwal (Suhas Ahuja). Once he learns of Armaan's death, Shashi takes off with the cash, leaving behind a mistress, Mallika (Aditi Vasudev). Shashi's friend, Tehmur (Nawazuddin Siddiqui), steals Shashi's discarded sim card. Shashi begins blackmailing Sanjay. In panic, Sanjay employs some thugs to murder Shashi. Tehmur begins to use Shashi's old sim card to blackmail Sanjay with Shashi's murder.

Meanwhile, Roshni seeks solace from a medium (Shernaz Patel) who is in touch with Karan's soul. One night, Surjan is propositioned by an escort, Rosie (Kareena Kapoor). He declines Rosie's advances but asks her if she can become an informer. Through Rosie, Surjan finds out about Shashi's connection with the case. 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. Convinced of Armaan's link with prostitutes, Surjan focuses his search on the slums near the Hotel Lido. To speak unobserved, Rosie takes Surjan to a quiet place by the riverside and tells him that three years ago, she was picked up by Armaan and his friends, Sanjay and Nikhil (Prashant Prakash). However, she doesn't reveal anything more. Surjan tries to approach Nikhil for more information but discovers that Nikhil has been brain-dead after the incident three years ago. After a heated argument with Roshni, Surjan confides in Rosie, who comforts him by taking him to the Lido.

Tehmur is killed by the two thugs in Sanjay's employ. One of the thugs is captured by the police and reveals that Sanjay has been behind the murders of both Shashi and Tehmur. Surjan arrests Sanjay, who confesses that three years ago, Sanjay, Armaan and Nikhil had picked up an escort to celebrate Nikhil's birthday. While driving, 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. Both were badly injured. Armaan and Sanjay rushed Nikhil to the hospital but fearing scandal, left the girl unattended on the road. Sanjay had called Shashi to ask him to take care of her. However, 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 extort money from them by blackmail.

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 Surjan and Sanjay see Rosie standing ahead. In a re-enactment of Armaan's accident, Sanjay swerves the car into the river. With Sanjay already dead, Surjan struggles to get himself out of the car. Rosie appears underwater and saves him. At the police station, Surjan's superior advises him against reporting his incredible story. Surjan agrees to write in the official report that Armaan Kapoor'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 Roshni consoles him. The two are reconciled.