Plot

The lives of Calcutta's most powerful Gunday, Bikram and Bala, changes when Nandita enters it. Then a counter-force takes charge and a thriller unfolds.

The war of 1971 gave birth to Bangladesh and two young orphans - Bikram (Ranveer Singh) and Bala (Arjun Kapoor). They became Calcutta's most loved and most powerful GUNDAY. Nandita (Priyanka Chopra), the beautiful cabaret dancer, walked in and they fell head over heels in love with her. And then entered ACP Satyajeet Sarkar (Irrfan Khan), a law for every outlaw and a counter force for Bikram and Bala.—Yash Raj Films

Bangladesh becomes an independent nation after the 1971 war. Amongst those affected by the partition are two orphans: Bikram Bose and Bala Bhattacharya. Starving, Bikram and Bala are taken in by a man named Lateef (Pankaj Tripathi), who offers them to work for him, and illegally smuggle guns to other men. He cares for them until one day an army officer that they give guns to, tells Lateef to leave one of the two boys behind to work as his child sex slave or otherwise he'll take Lateef's daughter. Bikram hears this and tells Lateef that he'll stay behind in order to save Bala, his friend. Bala then comes back to save Bikram and kills the army officer. This makes them partners in crime; when the army chases them, Lateef is killed while trying to protect the duo.

They arrive in Calcutta by train and start their livelihood by working in a small restaurant. Bala gets into a fight with the owner who slaps him and calls him a refugee. They start looting trains of coal and selling coal in market at lower price.

As they grow up, Bikram (Ranveer Singh) and Bala (Arjun Kapoor) have started looting whole trains. In this process, they kill a famous coal robber, Dibakar (Deepraj Rana), who calls them "refugees". When Bikram and Bala loot one of Dibakar's trains, his men threaten them. Undeterred, they promise to loot his next train as well. When they arrive to loot Dibakar's train, he calls them "refugees," and a fight ensues. Before they kill Dibakar, Bikram and Bala tell him that they are Indians, not refugees.

Now having control of the coal business, they convert all their illegal trades to legal business with the help of Kali Kaka (Saurabh Shukla), who is also their lawyer. They become local heroes by building hospitals, donating to charities, and building schools. Their business dealings make them a target of the law. They also provide work and help to the poor, thus becoming white collared 'Gunday'.

A.C.P. Satyajeet Sarkar (Irrfan Khan) who is now summoned to Kolkata to catch Bikram and Bala, warns them that he will arrest them the day he finds a single evidence.

A businessman invites Bikram and Bala to the opening of his new club in Calcutta. He introduces them to Himanshu, his assistant. Then Nandita (Priyanka Chopra), a cabaret dancer, enters the boys lives and both Bikram and Bala fall in love with her. They decide that whomever she loves will marry her. After some persistent wooing, Nandita invites them to a theatre to tell them whom she loves. Bala gets into a fight there with a man who makes a disrespectful comment on Nandita and Bala shoots him.

Bikram asks Bala to run away for now so that he can be safe and promises not to meet Nandita until he returns. Sarkar warns Bikram that if Bala returns to Calcutta, he will be killed. Nandita tells Bikram she is in love with him and if he won't come to Durga Puja she will never see him. Bikram breaks his promise to Bala to meet Nandita. Bala finds out about this through one of his henchmen Himanshu (Anant Sharma) and returns to Kolkata during Durga Puja. On spotting Bikram and Nandita together, Bala shoots at Bikram in rage, but misses and the bullet hits Nandita. She is rushed to hospital and survives, but it breaks friendship between Bikram and Bala.

Bala then finds out that all their business is in Bikram's name, hence he angrily calls Bikram and asks for equal partition of business. He agrees and transfers half the business to Bala, even sharing the ration card which is proof of their Indian nationality. Bala then talks about dividing Nandita between them. Bikram gets angry and they both start fighting. Bikram wins but spares Bala, as he once saved Bikram when they were kids.

When Bikram proposes to Nandita, she says she cannot marry him unless he leaves his criminal life behind; Bikram agrees. A vengeful Bala blows up Bikram's coal mines and kidnaps Nandita.

As Bikram prepares to kill Bala, Sarkar asks Bikram to turn the state's evidence against Bala so he and Nandita can marry. Bala tells Nandita that he will kill her unless she leaves Bikram; Nandita retorts that she still loves Bikram after explaining the differences between him and Bala. She also clarifies that Bikram was waiting for Bala even when Bikram was with her.

Heartbroken, Bala apologizes to Nandita and returns her to Bikram. In reality, Nandita is an undercover police officer helping Sarkar arrest Bikram and Bala. When Bikram prepares to help Sarkar implicate Bala, he encounters the man whom Bala supposedly killed and learns that he is also an undercover police officer. Nandita tries to convince Bikram that he will be treated leniently by the law. He believes the law was responsible for destroying their childhood and innocence. Nandita reveals her identity to Bikram, and he realizes that she was a trap Sarkar set to separate him from Bala. When she asks him to surrender, he refuses and rejoins Bala.

Himanshu brings Bala into the coal mine to meet Dutta. Himanshu tells him that he is Dibakar's brother and saw him murdered by Bikram and Bala. He reveals Nandita's identity and tries to kill Bala, but Bikram rescues him, and Bala kills Himanshu. While trying to escape, they are then cornered by Sarkar and Nandita, who again tells Bikram that she loves him, and he should surrender.

Sarkar also tries to convince Bala to surrender. Bikram and Bala see a passing train and run towards it. As Bikram and Bala are inches away from catching the train, Sarkar and Nandita shoot at them. Ambiguous over their deaths, the story ends with Bikram and Bala as they narrate how they were, was and will always be the goons.