The Major Crimes Unit (MCU) is a fictional police squad in the Gotham Police Department, in the Nolan films continuity. The first commander of the unit was Lieutenant James Gordon, after the events of Batman Begins.
The second Nolan film, The Dark Knight, features the GCPD extensively. According to the viral marketing campaign for the film, Harvey Dent spearheads an initiative through his office to rid the department of corruption. The police have also cooled their animosity towards Batman, the official investigation jokingly placing Elvis, Abe Lincoln, and Bigfoot on their wall of suspects for Batman.
Commissioner Loeb is murdered when his drink is replaced with acid by the Joker as part of a three-way attack that also included bombing a judge's car and attacking a fundraiser for Harvey Dent. After the Joker is captured the first time, Gordon is appointed to replace Loeb as Commissioner by the Mayor. Also featured are three detectives, Gerard Stephens (played by Keith Szarabajka), Michael Wuertz (played by Ron Dean) and Anna Ramirez (played by Monique Curnen). While Stephens is a good and honest cop, the latter two are corrupt and involved in the mob (or, in the case of Ramirez, used to be an honest cop, but was placed in a tough situation involving her mother's life.). They help the Joker kidnap Rachel Dawes and Harvey Dent.
Dent and Dawes are tied up and placed near explosives. Batman rescues Dent but Dent's face is scarred while Dawes is killed. While Wuertz appears to show no remorse whatsoever for his crime, Ramirez is clearly devastated by the turn of events. Dent later kills Wuertz after the coin lands on the charred side (and partially for revenge), but he spares Ramirez after the coin lands on its good side (and partially because she needed money for her ill mother's hospital bills). He merely pistol-whips her in retribution. After Dent is stopped, Batman willfully takes the blame for Dent's crimes, ending the police's alliance with the Batman and reigniting their manhunt.
Harvey Dent, prior to becoming the district attorney, worked closely with Internal Affairs when starting out in his law career and was nicknamed "Harvey Two-Face", a name he takes up after his scarring.
Out of all nine Batman films, the Christopher Nolan series prominently featured the GCPD with a SWAT team mostly because of the series' realistic tone. (However, GCPD vehicles bear only the letters "GPD".)