Part One

Hoping to solicit help in laundering his funds, Gotham City mob boss Carmine Falcone meets with billionaire Bruce Wayne under the guise of repairing the relationship between their families. Bruce declines.

On Halloween, someone murders Johnny Viti, Falcone's nephew, and leaves a jack-o'-lantern at the crime scene. Gotham City PD Captain James Gordon suspects Falcone is responsible because Viti was planning to testify against him. Gordon, Batman, and District Attorney Harvey Dent make a pact to take down Falcone without breaking the law.

Catwoman leads Batman to Falcone's cash stockpile, with Harvey following. Based on a coin flip, Harvey decides to burn the money rather than move it legally and risk Falcone stopping them. In retaliation, Falcone hires triad member Mickey Chen to bomb Harvey's house. Harvey and his wife Gilda survive but are hospitalized. Chasing Chen down to the sewers, Batman runs into Solomon Grundy. Batman convinces Grundy to spare Chen and takes him to the GCPD for questioning. Lacking evidence of his involvement in the bombing, Batman and Gordon are forced to release him.

On Thanksgiving, Falcone's son Alberto sends Harvey a mocking "get well soon" card in his father's name. After finding out about this, an angry Falcone tells Alberto to never speak on behalf of the family again, especially to the Dents. Harvey escapes from the hospital and meets Gordon, who gives him a gun. That night, Viti's murderer kills Chen and his associates before leaving a Thanksgiving decoration behind.

By Christmas Eve, Gordon and Batman question Calendar Man in Arkham Asylum on the identity of the murderer who has now been nicknamed "Holiday". Calendar Man names Falcone, Sal Maroni, and Harvey as suspects and calls Batman's war on crime a "joke". Batman then realizes that Joker has escaped from Arkham. Not wanting Holiday to replace him as Gotham's most notorious criminal, Joker confronts Harvey in his home and threatens to kill Gilda if he is proven to be Holiday. Batman visits Maroni, who Joker also attacked. Meanwhile, Joker harasses Falcone, asking that he share any new information about Holiday. Falcone's bodyguard Milos Grappa chases Joker out of the building and is killed by Holiday.

At this point, Bruce suspects five people of being Holiday: Maroni, Falcone's sister Carla Viti, Joker, Falcone, and Harvey.

Bruce attends a New Year's Eve yacht party celebrating Gotham's children's clinic, hosted by Falcone, who calls out Bruce during his speech as the son he never had, angering Alberto. Bruce meets with Selina Kyle, who calls off their relationship due to their conflicting secret identities. Joker attempts to gas a concurrent celebration in Gotham Square using a stolen plane, hoping that Holiday is among the crowd. Meanwhile, Selina meets with Alberto to learn about the Falcone family. Alberto laments about never being respected by his father, who also rejected his fiancée from Oxford University. Batman foils Joker's scheme, and when Joker remarks that he "loves a good puzzle", Batman deduces that Alberto, who would benefit the most from killing his father's enemies and is known for his love of puzzles, is the killer.

At the yacht, Batman accuses Alberto of being Holiday, targeting Falcone's associates to gain power within the family. Alberto denies wanting control of the family business, citing he no longer wishes to be in his father's shadow. As the New Year starts, Alberto is shot dead by Holiday and falls into the water, where the yacht's propellers cut his body to pieces. Batman pursues Holiday, who eventually escapes via speedboat. As the ship is evacuated, Batman tells Gordon and Harvey to assign a protective detail to Falcone.

At Alberto's funeral, Falcone again pressures Bruce to help launder his funds. When Bruce refuses, Falcone introduces the woman accompanying him. Vines grip Bruce's arm as they shake hands and cause his eyes to turn green. The woman, revealed to be Poison Ivy, has taken control of him.

Part Two

In the three months since Alberto's death, the Holiday Killer has targeted the Falcone and Maroni families on Valentine's Day, Saint Patrick's Day, and April Fools' Day. Meanwhile, Bruce has signed much of his assets to Falcone under Ivy's influence. Catwoman subdues Ivy and rescues Bruce. Alfred calls the police and Bruce's lawyers to arrest Ivy and stop the transactions.

On Mother's Day, while investigating the murder of Chong, a black market arms dealer posing as a teahouse owner, the GCPD discovers he was supplying Holiday with firearms. Later that night, Scarecrow escapes from Arkham Asylum and injects Batman with fear toxin during a confrontation. Forced to relive his parents' deaths, Batman is eventually found by Catwoman and taken home.

Gordon and Harvey question Bruce about his family's connections to Falcone. Bruce recalls how, as a boy, he watched his father save Falcone's life following an assassination attempt by Luigi, Maroni's father. Bruce assures Gordon and Harvey that any relationship between his family and Falcone ended after the death of his parents in what he believed was retaliation for saving Carmine.

On Father's Day, Holiday kills Luigi, prompting Maroni to approach Harvey and offer to testify against Falcone in exchange for immunity. Catwoman later follows Falcone to a cemetery and sees him pay a hitman.

On the Fourth of July, Batman is captured by Scarecrow and Mad Hatter as they rob a bank for Falcone. Batman escapes and defeats them as they drop off the cash in the cemetery. Meanwhile, Falcone's hitman attacks Harvey and Gilda. Catwoman intervenes, but the hitman knocks out both of them. Harvey awakens to find the hitman dead and one of Holiday's guns nearby. He flees as the police arrive.

Carla Viti publicly accuses Harvey of being Holiday. While Harvey has Maroni in court, Batman meets Gordon and reveals that he found Holiday's guns in the Dents' basement and an Oxford University Pennant. At the court, Maroni accuses Harvey of being Holiday and throws acid in his face. Harvey is hospitalized but escapes and is picked up by Falcone's men. Harvey realizes it is a trap, and the two men are here to kill him for Johnny and Alberto's death. Harvey kills his guards and flees into the sewers, where he is nurtured by Solomon Grundy. On Falcone's birthday, Carla is killed by Holiday.

On Labor Day, Harvey and Grundy attack Maroni's prison convoy. Batman, disguised as a guard, subdues Grundy, but Maroni is shot by Holiday from another building, and all three criminals escape. Batman asks Catwoman about her obsession with the Falcone family. She confesses that Falcone is her father and only wants to know her mother's name.

Harvey, now calling himself Two-Face, and Grundy attack Arkham and free several inmates; Poison Ivy, Scarecrow, and Mad Hatter engage the GCPD while Two-Face, Grundy, Joker, and Penguin attack Falcone's building. They overwhelm Falcone's guards and his daughter Sofia. Two-Face prepares to flip a coin to decide whether Falcone will live or die. Batman and Catwoman arrive and defeat the rogues but cannot prevent Two-Face from shooting Falcone. Distraught, Sofia falls out a window to her death. Catwoman reveals her face to Falcone, who mentions the name "Louisa", and Batman inadvertently reveals his identity while offering medical help but Falcone declines. Two-Face turns himself over to Gordon, claiming responsibility for the murders.

Batman confronts Gilda, who was not only Holiday but also the woman Alberto spoke of the night he died. She hated Falcone, who forced Alberto into annulling their marriage and forced her into getting an abortion which ultimately rendered her infertile. Seeking justice, she married Harvey, believing he was her best chance at taking down Falcone, but decided to take matters into her own hands after realizing he could not embrace his demons as she did. Assured that Holiday is finished, Batman leaves, not answering Gilda when she asks if he plans on telling Gordon the truth.

On Halloween, children start trick-or-treating again. That night, Flash^{[N 1]} and Green Arrow^{[N 2]} visit Bruce.

Commercial performance

Part One earned $659,774 from domestic DVD sales and $2,950,796 from domestic Blu-ray sales, bringing its total domestic home video earnings to $3,610,570.^[7] Part Two earned $454,659 from domestic DVD sales and $2,100,180 from domestic Blu-ray sales, bringing its total domestic home video earnings to $2,554,839.^[8]

Critical reception

On review aggregator Rotten Tomatoes, Part One has an approval rating of 100% based on 19 reviews, with an average rating of 7.7/10.^[9] Part Two has an approval rating of 100% based on 13 reviews, with an average rating of 7.9/10.^[10]

Jesse Schedeen of IGN rated Part One an 8 out of 10: "Batman: The Long Halloween, Part One may not quite meet the high standard of Justice Society: World War II, but it's a well-crafted addition to the revamped DC Universe Movies line. It faithfully adapts the comic book source material while still veering in its own direction at times. It's difficult to imagine this adaptation working nearly as well if Warner Bros. Animation had tried to cram the entirety of The Long Halloween into one movie. With any luck, Part Two will be just as successful."^[11]

Zaki Hasan of IGN rated Part Two a 9 out of 10: "It's a compelling story adapted with care and performed with conviction. Taken together, both parts make for not merely one of the best Batman animated movies, but one of the best Batman movies, period."^[12]

William Fischer of Collider negatively compared the film's visual design to the more detailed and stylized artwork of the comics story arc, while acknowledging that the film's animators worked under different constraints than illustrators.^[13]