It's a nice quiet day at Arkham, that is until Joker is brought into the rec. room where Poison Ivy all ready is watching TV and promptly changes the channel on her. They wind up getting into an argument over what to watch to the point that the guard comes over and picks a channel for both of them to watch. It happens to be showing a news segment about a new casino being opened up by multi millionaire Carmen Kiser. Lots of guests have arrived for the unveiling including Bruce Wayne.
The Joker isn't all that interested until he learns what the Casino is called, Joker's Wild! A casino totally based on him! This just gets him totally rattled, and he starts angrily shouting and raving all over the rec. room. When the guard comes over to calm him down the Joker acts sick and is taken to the infirmary. The guard leaves him in an examination room to go find a doctor. Once alone, the Joker makes his escape totally convenes that the guard's a plain idiot and unaware that the guard is watching him, letting him escape! The Jokers continues on his escape, past two doctors who see him and try to stop him. Joker however gets his hands on some cleaning supplies and makes the floor slippery for the doctors and giving him the chance to get outside. Once there, he hopes a ride onto a passing semi truck and drives off into the sun set determined to destroy the casino and Carmen Kiser.
At the casino Alfred has arrived with Bruce's Batman costume, not really happy about staying at the Joker themed casino. Batman's not too happy about it either, but has made a discovery. He pulls back the wallpaper to revel different themed wallpaper, a medieval knight type theme. This points him to think that Kiser might be up to something and is determine to find out.
Batman goes and sneaks into Kiser's office to do some snooping. He finds out that Kiser had broken the bank trying to build the casino and his original idea was in fact a medieval casino. He also finds a file on the Joker and all the crazy stuff the Joker has done. Just then a man runs into the office catching Batman in the act. It's the guard from Arkham that let Joker escape! He lunges at Batman, but Batman just throws down one of his gas bombs, leaving the guys daze wandering around room looking for while Batman leaves through the ceiling with the information he found.
By this time the real Joker has arrived at the Casino and is rather impressed about how much of it dedicated to him. He also get mistaken for on the employs and sent to deal at a card table. The Joker decides to take advantage of the situation and have a little fun. Of course his "fun" gets seen by a security camera. The guard watching sees him acting weird calls Mr. Kiser over to show, telling him he's going to call security on him. Kiser however doesn't seem too worried about it. It fact he seems rather happy about it and tell the guard to let him be. Bruce also happens to be in the casino and over hears just how much fun the Joker is having and wanders by his table. The Joker invites him to play him and Bruce happily accepts. The Joker recognizes him right at the start, as Bruce Wayne. Bruce however "innocently" starts criticizing about how awful the scenery is here around the casino. This gets Joker just a little bit peeved. Then Bruce does the unthinkable and beat Joker at the game, just totally irritating the Joker. Bruce leaves with his money and mentions to Alfred that he knows the Joker's here.
Batman comes looking for the Joker, only one problem. All the male employees are dressed up like the Joker, so it's kind of hard to find the real one. Fortunately the real Joker sees Batman and takes it as his cue to cash out. Batman sees him and takes off after him. Joker hijacks a car and drives out the back with Batman close behind. Batman manages to grab on to the car but the Joker jumps out and heads, making the car crash into a nearby sight setting it on fire. Batman barley has time to jump off and into the water. Totally safe from the explosion the Jokers watch happily, commenting that's it a great start for what to come.
The Joker goes and sneaks into an area still under construction, a Joker themed amusement park to give Kiser's casino a real blow-out opening, as he sets up him bomb. Kiser however is watching him from his really happy about the whole thing. He goes and orders his helicopter to get ready to leave with and starts packing his brief case, including a whole big wad of cash! Just as he's about to leave, Batman walks in. Batman points out what Kiser's really up to, he wants the Joker to destroy the casino so Kiser can collect the insurance money since he's practically broke after he tried to build it as a medieval themed resort. Kiser however has an ace up his sleeve and simply electrocutes him. He then calls in the phony cop and another crony to send Batman down to the Joker. When Joker sees Batman staggering out of the elevator, Joker goes and hit him on the head with a board, thinking Batman still recovering from the explosion and has merely come down to try and stop him.
Batman wakes up to find himself on one of the rides, a large spin table. The Joker shows him that when he spins the wheel, the casino, Batman and Kiser will all be blown sky high. Batman however tells Joker the truth, about how Kiser want him to blow it up so he can collect the insurance money. Joker gets mad and stops the bomb, deciding to take it Kiser man to clown. However, he still has plans for Batman, as he starts the wheel and throws in a grenade. Once Joker leaves, Batman merely pulls out his grapple and throws the grenade into a Statue Joker's mouth. The ride gets destroyed and Batman able to get himself free.
By this time Kiser has made it to his helicopter and orders the pilot to get going. The Pilot "smiles" and takes off. Batman arrives just in time to see the helicopter get airborne. He also sees the pilot on the ground next to him. The pilot says that a clown jumped and now took off with Kiser.
Above, the helicopter merely hovers around the platform, not going anywhere. When Kiser ask what going on, the Joker takes off his disguise and tells Kiser about how wonderful his scheme was, pulling out a gun. Before Joker can do anything though, Batman hitches ride with the help of his Bat-glider. Joker goes and starts flying the Helicopter Joker trying to shake him off. He manages to get Batman to crash and fall down into a Giant Joke mouth. Joker watches happily, thinking that Batman is now finally dead, but Of course it was just eh Bat-glider and Batman hanging outside the Helicopter. He goes and pulls himself up into the cockpit and he and the Joker began to rumble, while Kiser looks on in fear. During the struggle, Joke accidentally causes the Helicopter to fall, crashing into the Casino. Joker immediately tries to get away. Batman throws out a rope and trips him causing Joker to hit the jack pot, literally.
Back at Arkham, the Joker angrily watches the news report about his capture and goes to change the channel. Poison Ivy and a couple other inmates kindly suggest he changes it back, Joker happily changes it back just in time to the see the footage of him being returned to Arkham.