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 and the hand gun 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 newly elected District Attorney Harvey Dent swear 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 roses to Harvey with 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 for protection. That night, Viti's murderer kills Chen and his associates before leaving the pistol and 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 him 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. Batman arrives and finds a Christmas snow globe, the pistol and Joker playing cards next to Grappa's corpse.
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 crop duster 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 escapes via speedboat leaving behind the gun and a Champagne glass. As the ship is evacuated, Batman tells Gordon and Harvey to assign a protective detail to Falcone. Facing the fact that Joker and Alberto were not Holiday, the three wonder who Holiday is and who is next on his hit list.
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 is Poison Ivy and 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 tries to kill Two-Face with his own gun, but fails. She then trips over Poison Ivy's vines and despite Catwoman's efforts, 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, which Falcone declines before dying in Bruce's arms. Two-Face turns himself over to Gordon, claiming responsibility for the murders.
Batman confronts Gilda, who was both Holiday and 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. [N 3]
