As a ballerina effigy dances in her glass dome, a strange, armored man talks to the small dancer, promising a revenge against a "monster" for taking her from him.
Later on, Summer Gleeson gives a report on a series of mysterious heists pulled at various offices of GothCorp, all with the same M.O.: a "freeze gun" that creates a cold wave capable of generating thick sheets of ice and snow. Ferris Boyle, GothCorp's CEO, says he doesn't know what the mysterious perpetrator has against GothCorp, "the People Company," but hopes any differences can be patched up.
In the Batcave, Batman examines a list of the stolen devices, and finds that, when combined, they form a larger version of the freeze gun, large enough to become a fully-operational freezing cannon to the extent of being a city-wide threat. However, the machine is still missing one component, meaning Batman knows where the thieves will strike next.
That night, an armored vehicle attacks the GothCorp installation in question. When the Batmobile arrives, a freeze ray from the van creates a sheet of ice that causes the car to spin out of control, into a barely-controlled crash. Batman exits the car and engages the thieves: their ringleader appears, a man in a strange suit of armor calling himself Mr. Freeze. He fires his freeze gun at Batman, but misses and accidentally hits one of his own men in the legs, before managing to freeze Batman. Freeze orders his men to leave his comrade behind, and they escape. Batman manages to shatter the ice on himself, and is forced to take care of the thug, who is dying of hypothermia, rather than pursue Freeze.
After using a special bath to revive the man and melt the ice sheet on his legs, Batman — who has himself developed a cold from the encounter — visits Gothcorp as Bruce Wayne, hoping to learn who might have a grudge against it. Boyle says the only person he can think of is dead: a former research scientist employed by the company whose funding was cut, and who apparently died in a laboratory accident. When Bruce expresses mild surprise, Boyle, in private, reveals his true colors: "Look, Bruce, that 'People Company' line is great PR, but when the wage slaves start acting like they own the place, it's time to pull the plug." As Bruce is leaving, Boyle comments that he is to be presented with a humanitarian award.
Posing as a security guard, Batman sneaks into Gothcorp's offices and finds a security camera tape with footage of the accident: on it, a man named Victor Fries records that he has put his wife, Nora, into cryogenic stasis after she became terminally ill, to give himself time to research a cure. Suddenly, Boyle and a pair of security guards burst in. Boyle says that Fries's funding has been cut and he is using company equipment without authorization. He orders his guards to disconnect the equipment, despite Fries's horrified objections that Nora will die if they do so. In a panic, Fries seizes one of the guard's guns and orders them to stay back. Scared, Boyle attempts to reason with Fries. Fries lowers the gun — and Boyle kicks him in the chest, sending him crashing back onto a table of chemicals, which fill the room with vapor. As Boyle and his guards flee the room, Fries drags a hand over his wife's tank, calling her name. Watching this, Batman can only mutter "My God!", when Fries — now Mr. Freeze, appears behind him and blasts him with his cold gun.
Batman is kept prisoner in Freeze's hideout, partially frozen and without his utility belt. Freeze's men have finished assembling the giant cold gun, with which Freeze plans to attack Boyle's award ceremony. Freeze explains his suit: after the accident, he is incapable of living outside of a sub-zero environment, which the suit maintains.
After Freeze leaves, Batman manages to free himself. At the building, Freeze's cannon opens fire, covering the lower part of the building in ice. Freeze tells his men to go on firing until the entire building is covered, but Batman arrives and barely stops the cannon. Unwilling to admit defeat, Freeze smashes a fire hydrant and uses his gun to convert the fountain of spraying water into a column of ice that lifts him to the top floor of the building. Smashing his way into the awards ceremony, Freeze confronts Boyle and begins freezing him slowly from the legs up. He has just reached Boyle's waist when Batman arrives and distracts him. However, Freeze reveals that his suit's circuitry also triples his strength, and Batman is outmatched.
As Freeze holds Batman aloft, helpless, Batman remembers he is carrying a thermos of hot chicken soup that Alfred gave him for his cold. He dumps the soup onto Freeze's helmet, and the temperature difference causes the helmet to crack and shatter, letting the room-temperature air into Freeze's suit and paralyzing him. Freeze laments that he has been denied justice, but Batman says he won't be: he gives Summer Gleason the video tape of Fries's accident, then leaves, without freeing the still-shivering Boyle.
In Arkham, Freeze laments above the same ballerina effigy, and asks Nora to forgive him for failing to avenge her.