Mike Pillsbury [Michael Shulman] is a teenage boy who believes that he is an alien and does not belong on Earth. He is injured during a football game and has a vision of an alien, which makes him question whether football is the right fit for him. His father, a former football star, urges him to persevere, adding pressure to conform to expectations even as Mike feels out of place.
Katelyn Sandman [Erika Christensen], a popular girl at school, reaches out to Mike for help decorating the upcoming Halloween dance. Their budding connection lightens Mike’s mood, but trouble arrives when his rival, Scott Schriebner [Marcus Turner], a football teammate and Katelyn’s friend, sabotages the dance’s light and music setup. The party falls into mayhem, and a frustrated Mike storms off, sending a desperate message into space via a satellite dish in hopes of being rescued. A bolt of lightning then destroys the dish, leaving his plea unanswered and isolating him further.
The next day, an alien dog named Barnabus [Malcolm McDowell] appears, speaking through a translating device. He reveals that, because of Mike, a stargate door has been opened. Barnabus explains that he represents a galactic disaster-relief organization and that he has arrived to take Mike off Earth. He warns that time is limited, as other aliens with ulterior motives are traveling through the stargate in search of Mike.
Mike’s reality becomes even stranger when The Bom [Bruce Lanoil], an alien lawyer, materializes with a blunt demand: sue Earth for millions of galactic credits for pain and suffering due to the planet’s alleged substandard living conditions. During a phone call with Katelyn, Mike finds himself distracted by The Bom’s odd eating habits, which convinces Katelyn that he’s not listening to her. The Bom leaves in a fury after Mike refuses to pursue a lawsuit. Nick [Adam Wylie], Mike’s friend, becomes convinced that his buddy is losing his grip on reality, especially as more alien visitors arrive.
Barnabus informs Mike that he opened a “can of worms” by sending his space message, signaling that Earth has progressed technologically and might lose its protection as a primitive planet. Despite the danger, Barnabus offers to take Mike somewhere far away to be alone, but first Mike tries to repair things with Katelyn. The Loafer Alien [Wally Wingert] interrupts this moment, proposing to act as Mike’s galactic representative and even suggesting a reality-TV future for his life as an immigrant. Mike declines the offer.
A flood of alien visitors arrives with offers for Mike, disorienting him further. Katelyn visits him and learns about the strange visitors, and Mike becomes determined to find a way off the planet. Just then, a Thoad — a dangerous alien known for capturing specimens — approaches, complicating matters. Nick’s younger brother Jay [Andrew Ducote] is suddenly pulled into the stargate and taken to the Thoad’s home planet, triggering Barnabus’s warning that the Thoad will keep abducting beings until he finds the perfect specimen.
To protect Mike, the children enlist Scott as bait to lure the Thoad through the stargate. Scott is initially skeptical, but the kids convince him that he’s the key they need. Barnabus and the others manage to slip through the stargate along with the three children, landing in a cave that houses the Thoad’s zoo of captured species from across the galaxy. Among the captives is an alien that resembles the ones Mike had imagined, hinting at a shared memory or knowledge he didn’t fully understand.
The Thoad, in his human guise, confronts Barnabus and the group. He shifts into his frog-like alien form but is briefly contained within a cage. Mike uses the Thoad’s key to release the imprisoned specimens, including Scott and Jay. Barnabus and the kids return to Earth, but the stargate remains open long enough for the Thoad to pursue them. Barnabus calls in intergalactic police to arrest the Thoad. As the police arrive just before the Thoad can drag Mike into the stargate, Barnabus emits a decisive bark that signals the moment of capture.
Back on Earth, during a football game, Barnabus informs Mike that the transmission he sent was deemed accidental and Earth regains its status as a protected planet. Though Barnabus offers to take Mike with him, Mike chooses to stay on Earth, saying farewell to his unusual but enduring friend and returning to the life and home he loves.
