Bruce Wayne returns home to Gotham City after 12 years abroad, training for his eventual one-man war on crime; Lieutenant James Gordon moves to Gotham with his pregnant wife, Barbara, after a transfer from Chicago. Both are swiftly acquainted with the corruption and violence of Gotham City, with Gordon witnessing his partner Detective Arnold Flass assaulting a teen for fun.
Bruce goes in disguise on a surveillance mission in the seedy East End, where teenage prostitute Holly Robinson propositions him. He is drawn into a brawl with her pimp and several prostitutes, including dominatrix Selina Kyle. One of the two reporting police officers shoot him and take him in their squad car, but a dazed and bleeding Wayne maneuvers his handcuffed hands in front of himself, and demands the police get out. The cops try to subdue him, but the ensuing struggle causes the police car to careen out of control, and flips. Wayne flees, but not before dragging the police to a safe distance. He reaches Wayne Manor, barely alive, and sits before his father’s bust, requesting guidance in his war on crime. A bat crashes through a window and settles on the bust, giving him inspiration.
Gordon works to rid corruption from the force, but on orders from Commissioner Gillian Loeb, several masked officers attack him, including Flass, who threatens Gordon’s pregnant wife. Gordon tracks Flass down, beats him up, and leaves him naked and handcuffed in the snow.
As Gordon becomes a minor celebrity for his bravery on the job, Batman strikes for the first time, attacking a group of thieves and gaining experience. Batman soon works up the ladder, even attacking Flass while he was accepting a bribe. He gains a reputation of being a supernatural being and inhuman, due to his use of speed and darkness to conceal himself. Two months after Batman arrived, the crime and corruption has declined. After Batman interrupts a dinner party attended by many of Gotham’s corrupt politicians and crime bosses, including Carmine "The Roman" Falcone to threaten their criminal organization, Loeb orders Gordon to bring him in by any means necessary.
As Gordon tries in vain to catch him, Batman attacks Falcone, stripping him naked and tying him up in his bed after dumping his car in the river. Assistant district attorney Harvey Dent becomes Batman’s first ally and he conceals this from Gordon.
Detective Sarah Essen suggests Wayne as a Batman suspect and she and Gordon witness Batman save an old woman from a runaway truck. Essen holds Batman at gunpoint, but Batman disarms her and flees to an abandoned building. Loeb fraudulently orders a bomb dropped on it, forcing Batman into the fortified basement. A SWAT team is sent in, led by trigger-happy Lieutenant Branden, whom Batman attempts to trap in the basement. Branden manages to climb out of the trap through a collapsed chimney, and joins in the gun battle. Enraged as the team’s careless gunfire injures several people outside, Batman beats the team into submission, but is wounded during the fighting. Using a signal device to attract the bats of his cave to distract the police and conceal himself, Batman escapes amid the chaos. Selina Kyle, after witnessing him in action, dons a costume of her own to begin her life as Catwoman.
Gordon has a brief affair with Essen, while Batman intimidates a drug dealer for information. The dealer goes to Gordon to testify against Flass, who is brought up on charges. Loeb blackmails Gordon with proof of his affair against pressing charges. After taking Barbara with him to investigate Wayne's connection to Batman, Gordon confesses the affair to her. Bruce avoids Gordon's suspicions by appearing with a woman over and heavily drinking, though he is actually faking all of it.
Batman sneaks into Falcone’s manor and overhears a plan against Gordon but is interrupted when Catwoman, hoping to build a reputation after her robberies were pinned on Batman, attacks Falcone and his bodyguards, aided by Batman. Identifying Falcone’s plan as the morning comes, the un-costumed Bruce leaves to help Gordon.
Gordon tries to rebuild his relationship with his family after Essen leaves Gotham. While leaving home, Gordon spots a motorcyclist enter his garage. Suspicious, Gordon enters to see Falcone’s nephew Johnny Vitti and his thugs holding his family hostage. Gordon realizes if he lets them go, they will most likely kill his wife and son. Therefore, Gordon shoots the thugs and chases Vitti, who has fled with his baby son James Gordon, Jr. Bruce Wayne, on a motorcycle, also rushes to chase Vitti. Gordon blows out Vitti's car tire on a bridge and the two fight, with Gordon losing his glasses, before Vitti and James Gordon Jr. fall over the side. Bruce leaps over the railing and saves the baby. Gordon realizes that he is standing before an unmasked Batman, but says that he is "practically blind without [his] glasses" and lets Bruce go.
Gordon and his wife start attending marriage counseling. Loeb is forced into early retirement and that means he is arrested and on trial. Falcone is in the hospital and will be heading to prison pretty soon when he heals, while Flass makes a deal with prosecutors to testify against him. Gordon, meanwhile, is promoted to Captain. When a criminal who "calls himself the Joker" threatens to poison the city's reservoir, Gordon summons Batman with the Bat-Signal and waits on a rooftop for the Dark Knight to arrive.Ben McKenzie as Bruce Wayne / Batman
Bryan Cranston as Lieutenant James Gordon
Eliza Dushku as Selina Kyle / Catwoman
Jon Polito as Commissioner Gillian B. Loeb
Alex Rocco as Carmine Falcone
Katee Sackhoff as Detective Sarah Essen
Jeff Bennett as Alfred Pennyworth
Grey DeLisle as Barbara Eileen-Gordon (credited), Vicki Vale (uncredited)
Robin Atkin Downes as Harvey Dent
Keith Ferguson as Jefferson Skeevers
Danny Jacobs as Flass's Attorney
Nick Jameson as Officer Stanley "Stan" Merkel
Liliana Mumy as Holly Robinson
Pat Musick as Louisa Falcone
Stephen Root as Lt. Branden
Fred Tatasciore as Detective Arnold John Flass, Johnny Vitti
Producer Bruce Timm noted that the adaptation of the film was relatively straightforward due to the cinematic nature of the original story arc. Bryan Cranston originally turned down the role as James Gordon because he was unfamiliar with both animation and classic comics. Cranston said "I wasn't aware of this level of storytelling in animation."
Batman: Year One received positive reviews upon its release. Rotten Tomatoes gives the film a score of 86% based on reviews from 7 critics, with an average rating of 6.8 out of 10.
An IGN review of the film, after its Comic-Con screening, praised the voice actors and concluded with, "This is real, serious adult entertainment that should satisfy longtime fans and newcomers as well." Another review from IGN panned the film, describing it as "dead on arrival – a lifeless bore with stale voice work and a disjointed, sporadic narrative that was best kept on the pages of Frank Miller's stellar graphic novel." Tommy Cook of Collider called the film a "faithful adaptation". The A.V. Club gave the film an A-, saying "Batman: Year One is a stellar adaptation, copying Miller’s words and Mazzucchelli’s images almost verbatim at times." Concluding that, "It all recalls what it felt like to read Batman: Year One for the first time, and sense that this was a story that had always existed."
Cinemacrazed criticized the short run time of the film as its main downfall. James O'Ehley of SciFiMoviePage notes that the faithfulness to the source material works for and against the film, with voiceover and dialog slowing down the action, and he goes on to say how the animation could be bolder, the voices gruffer and the sound more stirring but that overall the film is better than other DC animated films.
In an article for The Missing Slate discussing the influence of the comic version of Batman: Year One on film depictions of Batman, Michael Dodd praised the casting of Bryan Cranston as Jim Gordon. Referencing Cranston's famous role as Walter White on Breaking Bad, he argued that the choice of casting "truly encompassed the character's determination and downright badass attitude in the comic Year One".
The DVD and Blu-ray release includes a short animated film titled Catwoman. In the film, Catwoman deals with the crime boss Rough Cut (voiced by John DiMaggio) while trying to stop a cargo shipment. There is also a sneak peek for the film Justice League: Doom, two featurettes, a commentary, a digital comic book, two Batman: The Animated Series episodes ("Catwalk" and "Cult of the Cat"), a standard edition of the film, and a high definition edition of the film.
On August 11, 2015, Warner Home Video re-released the film on a combo pack, which includes a DVD and Blu-Ray copy, a digital copy, and with the graphic novel it was based on.
Ben McKenzie would later go on to play James Gordon in television series Gotham.