Evening settles over the small Arizona town of Cactus Flats as the strip lights glow and a kid named Mike Powers [Spencer Vrooman] rides his bike along the edge of town. A streaking, unusual light cuts across the sky, and Mike stops to chat with Barney [Alfred Dennis], the friendly owner of the local pet shop. Barney asks what he’s wished for, and Mike replies with a simple desire for a pet turtle. Barney’s playful quip about retirement lands as he finishes locking up; soon after, the shop’s dogs bark at something unseen. The pink glow descends toward the storefront, and the backroom lights up with an otherworldly hum. Barney opens the door to reveal a man and a woman in flamboyant cowboy getups with enormous hats, speaking in a strange rasp. They offer Barney a suitcase stuffed with hundreds of dollars in exchange for his shop, and Barney wordlessly agrees to the deal.
Meanwhile, a family—the Yeaghers, Joe and Marilyn and their children Charlie and Dena—are arriving in town under witness-protection. They’re relocating from Brooklyn and taking new identities as the Vincenzas. Their handler, Marshall Dave, posing as an uncle, instructs them to sever outside contact and keep their new names, wary of Tony Marino, a jailed criminal who will be released and whom Joe “ratted out.” At the prison, Marino plots with his crew, Babe and Curly, about “rats” that must be exterminated before his release, or else be exterminated themselves. Back home, Marilyn’s slow longing for their old dog Rocko hints at a stubborn sense of loss.
In the pet shop’s backroom, the newly minted owners—Mr. Zimm and Mrs. Zimm—have transformed the space into a high-tech, spaceship-like chamber filled with alien devices and a lineup of otherworldly creatures. The aliens respond to the Zimms’ commands and appear noticeably more intelligent than earthly pets. The Zimms threaten the creatures and demand they convert into more terrestrial forms to avoid drawing attention, then administer special vitamins to keep them under control.
At the grand re-opening, Mike and his friend Nicky explore the store, hoping to find Barney. Mike spots a turtle he wants but has no money, while a security camera tracks the boys from above. Mr. Zimm initially tells Nicky that an escaped alien isn’t for sale but soon relents, inviting him to come after hours for free pets. The children eventually return, promising to take responsibility for the free pets, and it becomes clear the Zimms are surveilling the kids through cameras and other gear to gauge how much human air they can harvest for the alien pet market. Up north, Marino’s crew heads toward Cactus Flats, intent on reacting to the Yeagher family’s presence.
Dena’s game of fetch with Gizel reveals the alien’s power as the creature briefly shifts into an alien form, a signal that similar transformations are happening in households across town. Mike visits Dena and speculates that these animals don’t belong in any encyclopedia, urging the kids to gather and uncover why the Zimms have handed out all these pets for free.
The Zimms boast about a transport device and admit they’ve duped the children by withholding vitamins. They plan to take back the pets via a cosmic exchange, selling them to pay bills. The kids converge at Mike’s home, pulling a fast one on the adults by convincing Charlie that Mike’s older sister Gwen is available and appealing. To Mike’s dismay, Gwen’s real-life appearance is different from a previous photo. As Mike tries to keep focus, the pets begin to show signs of illness, prompting the kids to scramble a response by improvising meals for the creatures. The animals seem to perk up briefly but soon sag again. Dena discovers a contract clause that allows the pets to be brought back to be “fixed up” if they fall ill.
With their car running dry, Babe and Curly roll into town on foot for help. A call from Joe indicates that all the kids are missing, having disappeared into the pet shop. The kids return to the Zimm residence with the pets, administering vitamins and explaining that, per interstellar rules of commerce, they can only take as many pets as they leave behind—“Four critters for four humans.” The kids’ plan works, and the aliens begin to stumble as the pets spring to life and repeatedly trip up the Zimms. A dramatic moment occurs when Mr. Zimm’s hat is knocked off, revealing a bulbous forehead and a third eye, a sign of the creature’s otherworldly power as he tries to unleash “the business” with colored beams that paralyze the children.
The adults intervene, and Joe disrupts the scene by shattering the backroom glass to grant Dave and the others access. Mrs. Zimm is momentarily frozen by Joe’s misfire, while the alien children rally to resist. In the backroom, Alexis (Alexis) [Sabrina Wiener] instructs Pwing to fetch keys, and Trimble pries the bars apart enough for her to reach through. Gizel races back to the Yeagher home and briefly causes Mrs. Yeagher to faint. Once freed, Alexis liberates the other children, and together they marshal the alien machinery to seal the doors and keep both the Zimms and Marino’s men at bay. Joe, still feeling the effects of the Zimmer beam, shatters the shop’s glass to gain entry, while the Zimms press their assault. The Zimms plead to spare Dena, offering her as the most valuable, but the hat gets stuck, and Marino’s men seize Dena at knifepoint. The kids and pets team up to free Dena, and a final surge of activity activates the teleportation device, whisking the Marino brothers away.
The adults finally force the door open and collide with Mrs. Zimm, who seems to reappear as the two aliens whisper that the adults are less valuable, but at least their bills are paid. The transporter hums to life, the room glows, and the entire backroom folds into itself, becoming the same space once more. The Zimms shift back into their pink blob forms and flee, while Mike and Alexis stay behind as the others depart, leaving Pwing and Trimble behind in the hubbub. Outside, the town crowds watch the pink blob ascend into the sky. Charlie arrives in the family car, a lipstick-kissed mark on his cheek, while Gwen pursues him on a motorcycle.
Reunited with their pets, the Yeagher family returns home, grateful for safety and a sense of normalcy. Dena’s father earns high praise from her and from Marshall Dave, who assures the Yeaghers they are now protected from Marino. Gizel, left to roll in the mud, munches the damp earth, and Dena realizes that Gizel’s garbled murmur—clearly about the mud tasting like vitamins—implies that the alien pets may be fine after all.
