Plot

Held hostage by the powerful Falcone crime family, Gotham City is rife with crime and corruption. Adding to the chaos is the mysterious Holiday killer, who has been targeting the underworld and leaving a trail of terror - and body bags.

Inspired by the iconic mid-1990s DC story from Jeph Loeb and Tim Sale, Batman: The Long Halloween, Part One begins as a brutal murder on Halloween prompts Gotham's young vigilante, the Batman, to form a pact with the city's only two uncorrupt lawmen (Police Captain James Gordan and District Attorney Harvey Dent) in order to take down The Roman, head of the notorious and powerful Falcone Crime Family. But when more deaths occur on Thanksgiving and Christmas, it becomes clear that, instead of ordinary gang violence, they're also dealing with a serial killer - the identity of whom, with each conflicting clue, grows harder to discern. Few cases have ever tested the wits of the World's Greatest Detective like the mystery behind the Holiday Killer.—Pedro Borges

It's a dark time in Gotham City. Held hostage by the powerful Falcone crime family, the city is rife with crime and corruption. Adding to the chaos is the mysterious Holiday killer, who has been targeting the underworld and leaving a trail of terror...and body bags. Batman, Lieutenant Gordon and D.A. Harvey Dent race against the calendar as it advances toward the next ill-fated holiday. Based on the critically acclaimed graphic novel, Batman: The Long Halloween, Part One begins a twisted chain of events that will forever change the Dark Knight.—Anonymous

In Gotham City on Halloween, Carmine "The Roman" Falcone's nephew, Johnny Viti, is murdered by a mysterious figure who leaves a jack-o-lantern at the crime scene.

Gotham City Police Department Captain, James Gordon, summons District Attorney Harvey Dent and Gotham's vigilante Batman to investigate the murder. Batman follows Catwoman to Falcone's cash stockpile. Based on a coin flip, Dent decides to burn the money rather than move it legally. In retaliation, Falcone hires San Ho Hui Triad member, Mickey Chen, to bomb Dent's house. Both Dent and his wife Gilda survive, but Dent is hospitalized.

Batman chases Chen down to the sewers, where Chen runs into Solomon Grundy. Batman convinces Grundy to spare Chen and takes Chen to the GCPD. Lacking evidence of his involvement in the bombing, Batman and Gordon are forced to release him. Gordon advises Batman to learn more about being a detective.

On Thanksgiving, Falcone reminds his son, Alberto, that he will never inherit the family business. Dent escapes from the hospital and meets Gordon, who gives him a gun for protection. After Chen and his associates are killed by Viti's murderer, Gordon and Batman question Calendar Man in Arkham Asylum on the identity of the murderer, who is now coined "Holiday." Calendar Man names Falcone, Sal Maroni, and Dent all as suspects. He then says that Batman's war on crime is a "joke," and Batman realizes the Joker has escaped from Arkham.

Not wanting Holiday to replace him as Gotham's most notorious criminal, Joker confronts Dent in his home and threatens to kill Gilda if Dent is proven to be Holiday. Maroni advises Batman that if Joker is Holiday, he will inevitably target Falcone himself. On Christmas Eve, Joker harasses Falcone, warning him to divulge any new information about Holiday to him. Falcone's bodyguard, Milos Grappa, chases Joker out of the building but is killed by Holiday.

In the Batcave, Batman identifies Maroni, Falcone's sister, Carla Viti, Joker, Falcone, and an unnamed figure, implied to be Dent, as suspects.

Bruce Wayne 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. Bruce meets with Selina Kyle, who calls off their relationship due to their conflicting secret identities.

Joker attempts to gas Times Square from a stolen plane, hoping that Holiday is among the crowds. After Batman foils Joker, he returns to the yacht and accuses Alberto of being Holiday, targeting his father's associates to gain power within the family. Alberto argues he only ever wanted to live his own life, rather than being controlled by his father. The latter had previously rejected Alberto's fiancée from Oxford.

As the New Year hits, Alberto is shot by Holiday and falls into the bay, where he is cut to pieces by the propellers. Batman pursues Holiday, but Holiday escapes the yacht. As the yacht is evacuated, Gordon and Dent meet with Batman. He tells them to assign a protective detail to Falcone and vows to be a better detective.

In the post-credits scene, following Alberto's funeral, Falcone requests Bruce's help laundering his money, but Bruce refuses. Falcone then introduces his associate, who shakes Bruce's hand while vines emerge from her sleeve, and Bruce's eyes turn green.