In a universe where humans and peacefully coexist with what are usually considered docile zombies, society has adapted to treat these undead beings as second-class citizens, often referring to their condition as the "living-impaired" handicap. The story begins with Maggie Neard, a small-time thief who unexpectedly gets involved in a bizarre and dangerous world when she intercepts a call from the Coleman Corporation's Retirement Services for the Living-Impaired. This call is about collecting an unwanted zombie, and Maggie, along with her half-brother Karl Neard and his friend Freddy Mercks, decide to pose as zombie collectors to carry out their plan.
They pick up the zombie from the McKenna residence, but things quickly escalate when the zombie bites a family member, forcing the trio to act swiftly and decisively. In a desperate act of self-preservation, they have to decapitate the zombie to prevent further harm, leading to less-than-ideal payment from their black market contact, Don. Instead of a full payout, they only receive half because of the damage inflicted. Meanwhile, Hannity—a strict, militaristic officer working for Coleman—faces frustration from his subordinates Stanley and Rocco for repeatedly allowing the thieves to disrupt their zombie collection missions. Hannity's patience wears thin, and he orders them to recover the remaining $25,000 they owe him.
As their story unfolds, Freddy confesses to Karl that he's been harboring feelings for Maggie and plans to propose with a gaudy ring. The revelation sparks tension, especially when Freddy criticizes Karl, suggesting he’s a "chronic masturbator," which leads to a heated argument that gets interrupted when Stanley and Rocco capture the two. During the confrontation, Rocco's carelessness results in him accidentally shooting himself, transforming into a zombie right then and there. This incident prompts Karl to mention his grandmother, Mrs. Neard—a key figure later in the plot—sparkling an idea for Stanley to recover their owed money.
After being knocked unconscious during the capture, Karl and Freddy wake up at home with Maggie and discover a shocking videotape from Stanley and Rocco. The footage reveals that Mrs. Neard has been kidnapped, and the kidnappers are demanding a ransom. Desperate to make quick cash and save his grandmother, Karl, Maggie, and Freddy seek out Don once again, who refers them to the controversial performance artist Otto Maddox. Otto offers a lucrative deal: they will be paid $50,000 to steal the corpse of actress Debbie Jones, famous for playing Zelvirella, a vampira-like character.
Meanwhile, in the corporate world, Hannity presents his "Project Zoltan", an experimental gas designed to re-engineer and control zombies, to the Coleman board. During a demonstration by Dr. Judith West, things go awry when the undead test subject's head explodes unexpectedly. The board is disappointed, especially when the project is terminated. Oddly, Coleman CEO Bob Coleman dies in an accident involving a sex swing and is resurrected as a brain-damaged zombie. Seizing the opportunity, Hannity takes control of the company and moves forward with his plans, testing Project Zoltan on Coleman and Dr. West to see if it can turn zombies feral.
Seeking a solution, Karl, Maggie, and Freddy infiltrate Country Hill Cemetery only to find that Debbie Jones’s body is too skeletal to reanimate. Maggie then recognizes Stanley as her ex-boyfriend when he calls to demand their ransom. During that call, Rocco's careless shot results in the death of Mrs. Neard, turning her into a zombie. Karl recalls Jane, an undead online sex performer who resembles Zelvirella, and he convinces her to come with them. The group then faces a series of mishaps, including Karl's romantic encounter with Jane and an encounter with a state trooper, before bringing Jane to Otto Maddox’s private suite above a controversial performance art show.
At this point, Hannity unleashes Project Zoltan gas on the crowd, causing the zombies to become violently aggressive. Karl, feeling protective, calls off the deal with Otto, who is furious. Moments later, Jane chooses to leave with Otto, which angers Karl—especially when he confesses she is not the real Zelvirella. Their confrontation is cut short when an undead Mother Theresa appears and kills Otto. During the chaos, Don manages to escape with a briefcase full of Otto's money, but is soon overwhelmed by zombies on the show floor.
In a dramatic climax, Hannity captures Jane while Stanley, revealing himself as an undercover agent, unmasks Hannity and takes him at gunpoint. Freddy, in a heroic act, breaks Hannity’s neck only for Hannity to resurrect as a zombie and shoot Freddy. Maggie then intervenes decisively by decapitating Hannity with a buzzsaw, ending his rampage. In the chaos, Stanley steals the briefcase but gets bitten and turns into a zombie himself.
The story culminates in a world turned upside down; the viral effects of Hannity’s gas have led to what appears to be a global zombie apocalypse. Two weeks later, Karl, Maggie, Freddy, and Jane are surviving in a diner owned by Freddy's uncle Dave, avoiding arrest for the supposed bioterrorist attack. Meanwhile, Stanley wanders the wasteland, still clutching the briefcase, as chaos reigns around them, with Mrs. Neard and Rocco among the few who survive in this new, post-apocalyptic landscape.
