The film opens with Danila Bagrov (Sergei Bodrov Jr.) appearing on a television show with his two friends from the army. It is immediately known, that unlike the prequel's subplot, where Danila was an HQ clerk, he was is in fact a combat veteran from the First Chechen war (which immediately explains his non-amateur performance and skill in the first film). All three comrades now live in Moscow, where Ilya Setevoy (Kirill Pirogov) is a professional programmer who works for the State Historical Museum on Red Square whilst Konstantin (Kostya) Gromov (Alexander Dyachenko) works in the security department for the Nikolayevsky Bank. Danila himself reveals his ambition to enrol in medicine at the university.
After the program, the friends retire to an exclusive public bathhouse (the Sanduny) where Kostya reveals to his friends that his twin brother Dmitry is an ice hockey player for the Chicago Blackhawks and is being blackmailed by an American 'entrepreneur' Richard Mennis . According to Konstantin, his brother once played for his home club, the Kyiv Falcons before he was invited to play in the NHL and emigrated to the United States to play for the Chicago Black Hawks. Later he was signed by the Pittsburgh Penguins and from that moment he started to have trouble and difficulties with the Ukrainian mafia, who have been threatening and pressuring him. Dmitry (also portrayed by Alexander Dyachenko) was desperate and appealed to the local Chicago kingpin businessman Mennis (Gary Houston) for help and protection. Mennis took Dmitry under contract and granted him protection, but left Dmitry like an indenture servant. as all the proceeds are pocketed by Mennis. At the end Konstantin says that Mennis has come to Moscow to meet his employer, the owner of the Nikolayevsky Bank, Valentin Belkin (Sergey Makovetsky) to discuss a business proposal.
Almost simultaneously in a different part of Russia, that same television program was being watched by Danila's brother Viktor Bagrov (Viktor Sukhorukov) and their mother. Seeing how her older son has turned into a drinking police sergeant, whilst her younger one is now on TV, she pleads with him to travel to Moscow and seek his brother there, as his life back home was bringing her little happiness. The irony of the scene is that in the first film it was exactly the opposite, where Viktor was the role model. After the bathhouse, Danila meets up and begins an affair with a Russian pop singer Irina Saltykova (playing herself), who he met at the TV station and crashed at her apartment in the elite Kotelnicheskaya Embankment building.
The next morning Kostya approaches Belkin and pleads to remind Mennis about his brother. Belkin agrees, however Dmitry Gromov is of little concern to both as Belkin, being a Russian kingpin with money laundering partners, wishes to legalise their assets by investing in American companies, and needs Mennis's help to bypass standing law which prohibits foreign capital. The importance of the new friendship with Mennis prompts Belkin to remove Kostya altogether. That evening Danila stops at Kostya's apartment to discover his friend shot and sets out to avenge his friend. Knowing about his employer's lucrative deals, and Konstantin's desire to help his brother, there is little doubt who was behind the murder.
After himself being briefly arrested and beating up some thugs in jail, Danila pairs up with Ilya to begin their revenge. First he clears out his apartment, where it turns out that only a small stash of money, that he carried from the first film remain. A visit to the black market results in a CD with personal information about Belkin. A visit to a local neo-nazi friend of Ilya's gets them armed with trophy guns and grenades from the Great Patriotic War. Based in the museum at the Red Square, they almost miss his brother, Viktor, who arrived in Moscow earlier that day. With his help, Ilya manages to quickly steal a car for the job.
That day, a concert is held in an elite gimnasium, where Belkin's son Fedya is studying. Danila fools the security as latecomers, whilst Viktor distracts the other drivers/guards outside, making the impression that his "boss" i.e. Danilla is a very active member of the Russian underworld. Inside Danila arrives just to see Fedya being summoned to the stage where he reads a very patriotic poem, which deeply moves Danila. Intercepting him off-stage, he thanks him for the poem and introduces himself as his new teacher. With his cover in force, he approaches Belkin and invites him to the staffroom for a private conversation about the school's sponsor. One-on-one, at gunpoint he confronts him, and inquires about Kostya's murder. Belking reveals that it was not his doing, but under the pressure of Mennis, he talks of his illegal operations including smuggling of pornography and extortion. Afterwards he pleads for mercy, which Danilla grants, saying "it would be a shame to leave such a kid with no father".
After the run, the trio clear the museum, whilst Danilla gives Ilya his remaining money to purchase passports and tickets to Chicago. Upon Viktor's insistence they also take a Russian M1910 Maxim exponent. Belkin refuses to let Danila off, although it is revealed that Kostya's murder was unintentional, as he only wanted him sacked, however his stunt in the school now threatens his whole operation with Mennis. Belkin's thugs, reviewing the TV recording, first raid the museum, but arrive too late, issue orders to his contacts in the police to intercept the car, but Ilya's documents do not rouse any suspicion, when stopped by the traffic patrol. Danilla however decides to pass time with Saltykova, inadvertently bringing Viktor with him. Whilst Viktor tells Irina about this opinion on Russian pop music, Belkin's thugs find the stolen Volvo in a parking lot in front of the Kotelnicheskaya building. Saltykova's chauffeur Boris calls Danila and warns him, and the Bagrov brothers first ambush the mobsters and then lead them on a daring chase through central Moscow, into a closed ally, where Viktor makes a quick work of the cars with his Maxim gun. News of Bagrov's success enrages not only Belkin, but also his "partners" who begin having doubts in the security of their operation. Powerless, Belkin is forced to alert the Ukrainian mafia in Chicago, in case his thugs fail to intercept him in Moscow.
To avoid capture, the brothers fly to America separately, and Viktor passes by Belkin's thugs without any suspicion in Moscow, and the Ukrainian thugs in Chicago. Danila instead lands in New York City where he travels to the Russian Jewish Brighton Beach community. There he buys a cheap beat-up car to travel to Chicago by road, but it breaks down just outside Pennsylvania. Stranded he is saved when a trucker Ben Johnson (Ray Toler) picks him up. Despite Danila's limited English, the two become close friends and on his way to Chicago, Ben shows Danila much about American life. Upon their arrival in Chicago, Ben offers Danila to pick up a prostitute, however the bald Marylin, turns out to be a Russian Dasha (Darya Urgens Lesnikova). Though not interested in sex, he gives her some money, but the charity is quickly snatched up by her Black American pimp.
Back in Moscow, Belkin is still determined to catch Danila, however a background check revealed the bald man accompanying him (i.e. Viktor) is a professional assassin Tatarin and that he was on board the flight to Chicago. Paranoid, Belkin warns Manis and re-alerts the Ukrainian mafia in Chicago to find him. Simultaneously he dismisses his thug's suggestion to raid Saltykova, due to her fame, but instead commissions them to wire her phone. Foreseeing this, upon departure Danila created an alibi that he was travelling out of town for a few days and keeps deceiving Irina, and thus Belkin throughout the film.
Viktor meanwhile arrives in the Ukrainian diaspora district in Chicago quickly begins to spend his money wisely (and gaining more by beating up a police officer), enjoying the American lifestyle, making tours of the city dressed as Al Capone. Danila sticks to the mission, and first attempts to meet up with Dmitry Gromov, but is unable to catch him. Nor are his attempts to rendezvous with Viktor successful as Viktor is too much enjoying his life. Badly needing a translator he decides to find Dasha and travels to the Black neighbourhood. Just before he can run away with her, he is savagely beaten by Dasha's pimp's henchmen. The Police let him go on the basis of recognizance and he gets revenge by tricking the same group who beat him up into selling him weapons, which he steals by subterfuge. Afterwards Dasha's pimp attempts to get even with her but is in turn killed by Danila, leaving Dasha no choice but to go with him.