On the run from their formidable adversary, the planet-devouring Gorg, the Boov, a species with a unique talent for fleeing, discover Earth to be a prime candidate for their new "home." Under the leadership of Captain Smek, they initiate their seemingly "friendly" takeover, which involves relocating the humans—whom they consider simplistic and backward—by temporarily reversing the planet's gravity and vacuuming them from their homes. The humans are sent to a designated area in Australia dubbed Humanstown, while the Boov settle into their newly acquired residences in what they claim is a swift and bloodless conquest.
Among the Boov is Oh, a spirited and unconventional individual who dares to host a housewarming party in his apartment, disregarding the group's traditional aversion to him. The Boov have an intriguing trait of shifting colors according to their emotional states, adding to the whimsy of their character.
Close by is a preteen girl named Tip, who, determined to reunite with her mother, Lucy, embarks on an adventurous drive through her city, accompanied by her calico cat named Pig. While navigating her feelings of anger towards the Boov for their invasion, she is hell-bent on finding her mother after the chaos separates them.
In a twist of fate, Oh crosses paths with a Boov police officer named Kyle, who, like most of the Boov, rejects Oh's attempts at friendship. Excitedly, Oh sends out a mass invitation for his party, mistakenly hitting the "send all" button, which inadvertently informs every alien species in the galaxy, including the Gorg, of their location. With a countdown of 40 hours before the Gorg catch wind of their whereabouts, chaos ensues as every alien race aggressively pursues Oh.
To evade capture, Oh ducks into a convenience store, only to collide with Tip and Pig. Initially, she is furious with him for his role in the invasion, yet they realize they must join forces to rebuild her car, which has broken down. Ingeniously, Oh transforms it into a remarkable, hovering vehicle fueled by Slushies, dubbing it "Slushious." He offers Tip a ride under the condition that he helps her locate Lucy. Their journey necessitates a visit to the Boov Command Center in Paris.
Meanwhile, Smek is in a frantic quest to cancel Oh's disastrous invite, but finds himself struggling as Oh has set an unconventional password for his account. Oh reminisces about a peace meeting that Smek ran from, clutching the Shusher, a significant artifact embedded in his royal scepter.
As Tip and Oh's path entwines, they encounter challenges, including Oh's desires to abandon Tip for Antarctica, the only area free from Boov presence. Oh slowly grasps the depth of Tip's emotional plight in missing her mother. In an attempt to disguise Oh to aid them in Paris, Tip uses her makeup skills.
Upon reaching the Boov Command Center within the iconic Eiffel Tower, Oh manages to access his account and delete the mass invite just in time. Thanks to his ingenuity, they trace Lucy's whereabouts to Australia, where she is likewise searching for Tip. However, the other Boov catch up with Oh and Tip, and amidst the turmoil, Tip manipulates the gravity system, upending the entire Tower.
As they attempt to flee to Australia, a chase ensues with a Gorg ship looming ominously close. After a daring intervention where they manage to crash the Gorg ship, Oh retrieves a vital chip, reviving their Slushie-powered vehicle, propelling them toward Australia. Upon their arrival, they witness the Boov evacuating aboard their mothership. Tip yearns to find her mother, but Oh suggests they must escape. The emotional stakes rise when Tip realizes Oh lied about Lucy's safety, leading her to confront him about his betrayal.
In a heart-wrenching moment, Oh returns to the mothership destined for the Boov, but the Gorg ship intercepts them. Realizing he must take action, Oh uses the Gorg chip to steer the Boov ship away, drawing the admiration of fellow Boov. Smek, seeing the chaos, reluctantly acknowledges Oh’s leadership qualities, bequeathing the captaincy upon him.
Tip frantically roams the city in search of Lucy, with Oh ultimately rejoining her to help locate her mother. They succeed in reuniting, and as a massive Gorg mothership descends, Oh comprehends that the rock on the Shusher is the key to greater revelations. He bravely confronts the Gorg Commander, who turns out to be a harmless entity, grateful for the return of the rock, which harbors the species’ future generations.
Fast forward two weeks, the humans resume their lives in their original homes. Oh finally celebrates his long-awaited party, welcoming both humans and Boov alike. Tip shares her music, encouraging all to partake in the wonder of dancing, while other Boov join the festivities across the moon, and ships from distant planets, even the Gorg, flock to Earth to revel in Oh's joyful celebration.
