Intrigue

The Mayor Borg (Lee Wallace) of Gotham City orders District Attorney Harvey Dent (Billy Dee Williams) and Police Commissioner James Gordon (Pat Hingle) to increase police activity and combat crime in preparation for the city's bicentennial. The city is in massive debt, and the festival will cost $250,000. But the mayor is convinced that if the people line up the streets, the businesses will come back. Gordon tries to argue that the people are scared, but mayor asks him to control the mafia.

Reporter Alexander Knox (Robert Wuhl) and photojournalist Vicki Vale (Kim Basinger) begin to investigate reports of a vigilante nicknamed "Batman" (Michael Keaton), who is targeting the city's criminals. Vicki is a serious journalist who has covered war zones previously.

Batman waits at the top of Gotham's skyscrapers and when he hears a scream or sees a crime being committed, he reaches the location of the crime and uses the gadgets in his utility belt to disarm and defeat the perpetrators. Batman uses his cape to glide across town and has a bullet proof protective armor. Batman leaves the criminals alive and asks them to tell their friends about him. There have been 8 sightings of Batman in under a month. Knox and Vicki decide to attend Bruce Wayne's fundraiser, where Commissioner Gordon is supposed to make an appearance. They hope to get some clue from Gordon regarding Batman.

Mob boss Carl Grissom (Jack Palance), who has already been targeted by Dent, discovers his mistress Alicia Hunt (Jerry Hall) is involved with his second-in-command, Jack Napier (Jack Nicholson). Jack was getting arrogant that Carl was only an old man who could not run the city without Jack and felt immune from any retaliation from Carl.

Batman is in actuality Bruce Wayne, a billionaire industrialist who, as a child, witnessed his parents' murder at the hands of a mugger. Bruce meets and falls for Vicki at a fundraiser, and the two begin a relationship. At the fundraiser, Gordon receives an anonymous tip that Carl is cleaning out Axis Chemicals. He leaves the party immediately, which Bruce notices and follows Goron.

With the help of corrupt policeman Max Eckhardt (William Hootkins), Grissom sets up Napier to be murdered during a staged raid at the Axis Chemicals plant. Carl knew that Gordon would raid Axis Chemicals, and he sends Napier to stage their own raid to destroy all documents before the police gets them. They would later call it Industrial Espionage. However, Commissioner James Gordon arrives, takes command, and orders the officers to capture Napier alive.

During the ensuing shootout, Napier kills Eckhardt, after which Batman suddenly appears. The two struggle, and Napier is accidentally knocked into a vat of chemical waste. Batman flees, and Napier is thought to be dead.

Meanwhile, Napier survives the accident, but is horribly disfigured with chalk-white skin, emerald-green hair and green nails. He undergoes surgery to repair the damage, but ends up with a permanent ruby-red grin. Driven insane by his reflection, he reinvents himself as "the Joker", kills Grissom and usurps his criminal empire.

Bruce and Vicki go out on dates and Vicki is charmed by Bruce. She ends up sleeping with Bruce at his mansion. Vicki wakes up in the middle of the night to see Bruce performing intense exercises and is suspicious.

The Joker begins to spread terror in the city, first by lacing hygiene products with a deadly chemical known as "Smilex", which causes victims to laugh to death when used in certain combinations. Joker soon becomes obsessed with Vicki and lures her to the Flugelheim Museum, and he and his henchmen vandalize the surrounding works of art. Batman arrives and rescues Vicki, and the pair escape in the Batmobile. Batman gives information about Smilex to Vicki so she can warn the city via Gotham newspapers about the poisoned products.

Bruce meets with Vicki at her apartment, prepared to tell her that he is Batman. They are interrupted by the Joker, who asks Bruce, "Have you ever danced with the devil by the pale moonlight" before shooting him. Bruce, who was wearing body armor, escapes, and recollects that the man who killed his parents asked him the same question; he realizes that the Joker killed his parents. The Joker shoots Wayne, who survives thanks to a serving tray hidden underneath his shirt.

Vicki suddenly appears in the Batcave, having been let in by Bruce's butler, Alfred Pennyworth (Michael Gough). After avouching himself to Vicki, Bruce, chooses to battle the Joker for the sake of the city over their relationship. He then departs to destroy the Axis plant used to create Smylex.

Meanwhile, Joker lures Gotham's citizens to a parade honoring Gotham's bicentennial with the promise of free money (to the amount of $20 million). This turns out to be a trap designed to dose them with Smylex gas held within giant parade balloons. Batman foils his plan by using his Batwing to remove the balloons, but Joker shoots him down.

The Batwing crashes in front of a cathedral, which Joker uses to take Vicki hostage. Batman pursues the Joker, and in the ensuing fight, he explains that Napier killed his parents and thus, indirectly created Batman. This leads Joker to realize Batman is Bruce Wayne. Joker eventually pulls Batman and Vicki over the cathedral's roof, leaving them hanging while he calls in a helicopter. The helicopter is piloted by his goons, who throw down a ladder for him to climb. Batman uses a grappling hook to attach Joker's leg to a crumbling gargoyle that eventually falls off the roof. Unable to bear the statue's immense weight, Joker falls to his death while Batman and Vicki make it to safety.

Sometime later, Gordon announces that the police have arrested all of Joker's men, effectively dismantled what remained of Carl Grissom's mafia organizations, and unveils the Bat-Signal. Batman leaves the police a note, promising to defend Gotham should crime strike again, and asking them to use the Bat-Signal to summon him in times of need. Alfred takes Vicki to Wayne Manor, explaining that Wayne will be a little late. She responds that she is not surprised, as Batman looks at the signal's projection from a rooftop, standing watch over the city.