A man called Cameron Kaiser has opened a casino that he named Joker's Wild. The place was modeled after the criminal mastermind The Joker and it caused the wrath of the clown prince of crime, who escaped Arkham Asylum in order to teach Kaiser a lesson.
While watching TV from the rec room at Arkham Asylum, the Joker watches a news report about the opening of a luxury casino in the outskirts of Gotham City. The casino's owner Cameron Kaiser unveils the casino, "Joker's Wild", which is heavily modeled after the Joker's image much to the surprise and shock of everyone. Kaiser states that he is paying tribute to the joker symbol's classic roots, rather than the criminal himself no matter how it looked. This infuriates Joker, who realized that Kaiser is obviously stealing and profiting off his own image. Joker promptly escapes from Arkham and heads directly to his namesake casino.
Bruce Wayne attends as guest at Joker's Wild and is suspicious of Kaiser's motives. As Batman, he then infiltrates Kaiser's office and found files relating to massive construction bills for "Camelot" casino, and a dossier on Joker. The Joker arrive at the casino with intentions of destroying it in spite of appreciating the place's dedications to him. After causing some antics by passing as one of the casino's employees, Joker's presence is soon noticed by Kaiser, who was expecting him. To prove that the Joker is actually him, Kaiser and (unintentionally) Bruce Wayne provoke him by making unflattering remarks of the Joker. This causes Joker to burst out in anger and it gives away his identity. Bruce changes to Batman and starts looking for Joker. Realizing that he has been discovered, Joker uses the Jokermobile on display to escape from Batman.
As Joker plants explosives in the casino's basement, Kaiser prepares to leave but is then confronted by Batman. He tells Kaiser that he deduced why he constructed a casino modeled after Joker: Kaiser bankrupt himself building the "Camelot" casino before changing its theme in order to invite Joker's wrath to destroy it, thereby allowing Kaiser to collect the insurance money from the casino's destruction. Kaiser admits, but manages to incapacitate Batman with a electrical device and sends him to the basement, where Joker's captures and ties him to a giant roulette table attached to the explosives that are rigged to detonate.
When Batman wakes up, he reveals Kaiser's intentions to Joker, who then reluctantly deactivate the explosives and is resolved to chase Kaiser, but not before throwing a live grenade to Batman. Fortunately, Batman escapes by shooting the grenade away with his grappling gun. Joker hijacked Kaiser's helicopter and takes the casino owner with him, as he tells Kaiser that he decided to kill him and run the casino from behind the scenes. Batman chased the helicopter with his Batglider and manages to grab the helicopter. Batman tries to stop Joker and the two of them start to fight inside the helicopter, causing the aircraft to crash into the casino's front doors. From a kick delivered by Batman, Joker is sent crashing into a slot machine, which jackpots and covers him in coins.
Summer Gleeson reports the arrests of Joker and Kaiser, whose insurance fraud plot was exposed and was condemned for endangering his employees and guests. Joker bitterly watches the same news from Arkham's rec room and attempts to change the channel, but is forced to change it back by the other inmates.