Set in Miami, the novel follows a large cast of characters whose separate lives collide in increasingly absurd and dangerous ways, all converging around a suitcase containing a stolen Soviet nuclear warhead.
Puggy, a semi-professional vagrant, arrives in Miami after hitchhiking from Cleveland. He wanders into the Jolly Jackal, a decrepit Coconut Grove bar, where two petty criminals named Snake and Eddie steal his money and attack him. The bartender, Leo, intervenes, and a man named John, one of the bar's proprietors, offers Puggy work moving heavy crates he calls "equipment" into a locked back room. Puggy also finds a treehouse platform on the grounds of a wealthy Coconut Grove home and begins sleeping there, listening to soft flute music from the house each night.
The house belongs to Arthur Herk, a heavy-drinking bully and executive at Penultimate, Inc., a corrupt company. Arthur's wife, Anna, and her teenage daughter, Jenny, endure his nightly abuse. The family's undocumented housekeeper, Nina, locks her door each night after Arthur once entered her room uninvited and groped her. Nina plays flute music from her home country on a small tape player; Puggy, in his tree, listens to the same music and finds comfort in it.
Eliot Arnold, a divorced former journalist who runs a struggling one-man ad agency, endures a humiliating client who demands a crass beer advertisement. Eliot's seventeen-year-old son, Matt, borrows the car to "kill a girl" for Killer, a banned high-school squirt-gun assassination game. His target is Jenny Herk.
That night, Matt and his friend Andrew climb the Herk property wall carrying a realistic water gun. From his platform, Puggy notes they are the second pair of armed people to scale the fence. The first pair are Henry and Leonard, professional hitmen hired by Penultimate to kill Arthur, who has been embezzling from the company to cover gambling debts. When Anna opens the patio door, Matt charges forward with his squirt gun. In the chaos, Henry fires his rifle at Arthur, who dives off the sofa in time; the bullet destroys the television. Arthur flees into Nina's room, causing her to escape out the window. When Henry approaches Nina with his rifle, Puggy drops from his tree onto Henry's head and snatches the weapon.
Puggy carries the injured Nina to his platform. When she wakes, they share a tender connection, and she promises not to reveal his presence. Police officer Monica Ramirez and her partner, Walter Kramitz, respond to the 911 call, but the Herks are uncooperative and the investigation stalls. Eliot arrives to collect Matt and shares an instant connection with Anna, who confides about her unhappy marriage. Matt and Jenny exchange a CD, hinting at a mutual attraction.
Arthur, realizing Penultimate tried to kill him, plans to bring a weapon to federal authorities as leverage. The novel reveals that John and Leo are actually Ivan Chukov and Leonid Yudanski, former Soviet army technicians who became arms dealers and use the bar as a front for weapons sales. Arthur arrives at the Jolly Jackal demanding a missile. John does not have one and instead sells him a heavy metal suitcase containing a device he describes only as a "bomb." The device features a black box with foreign writing, electrical switches, and a steel cylinder; John is relieved to be rid of it.
Meanwhile, Eliot and Anna deepen their connection over lunch. Jenny arranges a quasi-date with Matt at CocoWalk, a Coconut Grove shopping center, where she will let him squirt her for the game. That evening, Jack Pendick, a delusional man twice rejected by the police for psychological unfitness, spots Matt's water pistol and opens fire with a real gun, convinced a crime is imminent. Matt and Jenny flee, and Monica later apprehends Andrew, who grabbed Pendick's dropped weapon.
Simultaneously, Snake and Eddie burst into the Jolly Jackal to rob it, arriving as Arthur and Puggy are leaving with the suitcase. Snake takes Arthur's wallet and watch, forces open the suitcase, and dismisses Arthur's warning that it is a bomb. Convinced it contains drugs, Snake drives Arthur, Puggy, and Eddie to the Herk house. Henry and Leonard follow.
At the Herk house, Snake takes everyone hostage. He sexually threatens Anna and Jenny, strikes Matt, and disarms Monica and Walter when they arrive looking for Jenny as a witness. Snake handcuffs Walter and Arthur to a steel entertainment unit, ties up the others, and flees in the stolen police cruiser with Jenny, Puggy, Eddie, and the suitcase.
FBI agents Greer and Seitz, tracking the missing warhead, learn from John at the Jolly Jackal that Arthur took the suitcase. At the Herk house, they find Walter handcuffed alongside Arthur, who is hallucinating from the toxic secretions of a toad he landed on during an escape attempt. Walter tells them Snake headed for the airport. During the drive to Miami International Airport, Greer reveals the truth to Detective Harvey Baker, who insists on joining them: The suitcase holds a modified Soviet nuclear warhead, one of two stolen from a Russian dismantlement facility, capable of destroying an entire city center.
At the airport, Snake buys tickets under a false name. At security, the checkpoint woman asks him to open the suitcase and turn it on. Snake flips three switches, unknowingly arming the weapon and starting a 45-minute countdown. The woman, pressured by long lines, accepts his claim that it is a portable garbage disposal and waves him through.
Puggy breaks free on the tarmac and runs back to alert Nina, Eliot, Anna, and Monica, who have pursued in Eliot's car. Monica and Matt chase the taxiing plane, grab its rear stairs, and climb aboard undetected. Greer arrives and grounds all departing flights, but Flight 2038 is already airborne. When Puggy tells Greer that Snake flipped the switches and small numbered lights appeared on the device, Greer orders two F-16 fighters scrambled from Homestead Air Reserve Base with instructions to shoot the plane down over deep water if the warhead cannot be removed.
Aboard the plane, Monica ambushes Snake, but a leg cramp buckles her and Snake shoots her, then pistol-whips Matt. Eddie, shot in the leg by Snake for refusing to cooperate, uses his remaining strength to shove the suitcase toward the open rear door. Snake dives after it, but the weight pulls him out of the plane and into the Atlantic. The pilot reaches his radio, and Greer screams to call off the fighters seconds before they fire. The warhead detonates deep underwater in the Gulf Stream, generating a rogue wave that strikes South Florida and the Bahamas, causing property damage but no deaths.
The next day's newspaper attributes the wave to a freak seismic event and credits Officer Ramirez with heroically confronting the hijacker. The night's other chaotic incidents are reported as separate, unrelated stories. Elevated radioactivity in the Gulf Stream is noted by oceanographers but never explained; the government denies everything.
The epilogue resolves each character's fate. The FAA shuts down Air Impact!, and a security contract for the airport goes to a subsidiary of Penultimate. Monica recovers and eventually marries Detective Baker; he tells her what was really in the suitcase, and they rarely speak of it again. Eddie joins a Hare Krishna temple. Arthur tries to report Penultimate's corruption but finds all evidence gone; he dies months later in a suspicious "fishing accident." Ivan and Leo are deported to Moscow, where they open a successful Starbucks. Anna divorces Arthur and marries Eliot, whose career revives when a New York agency hires him for a national campaign based on his beer ads. Jenny and Matt date briefly but settle into a lifelong friendship once their parents marry. Puggy moves into Nina's room, and the only Spanish he ever learns is
Te quiero, which proves to be all he needs.