Alex Rogan, portrayed by Lance Guest, is a teenage boy residing in a Southern California trailer park alongside his divorced mother, Barbara Bosson, and his young brother, Louis, played by Chris Hebert. With aspirations of escaping his current life and attending a prestigious college, Alex is devastated when he receives a rejection letter from his dream school. In his downtime, he finds solace through his favorite pastime: mastering the Starfighter arcade game, where players defend "the Frontier" against the evil "Xur and the Ko-Dan Armada."
One fateful evening, Alex achieves the highest score on the game by destroying the enemy's command ship, garnering a celebration from his friends and family, including little Louis. This intriguing feat captures the attention of the game's mysterious inventor, Centauri, who arrives in flashy style and invites Alex for a ride in his sports car, which shockingly turns out to be a spaceship. Centauri reveals his alien identity and whisks Alex away to the distant planet of Rylos, leaving behind his family and his girlfriend, Maggie Gordon. To cover his absence, an android replica named Beta, also played by Alex, takes his place.
Upon arrival in Rylos, Alex soon realizes that the Starfighter game is not just a game but rather a simulation designed to identify gifted individuals who can pilot real Starfighter ships against the impending threat posed by the Ko-Dan Empire, led by the treacherous Xur, played by Norman Snow. The stakes rise as Alex learns about the protective force fields known as the Frontier, which safeguard Rylos and other planets from invasion. The situation escalates when Xur publicly executes a traitor in a display meant to intimidate the Rylan populace into submission.
Despite his initial reluctance to embrace his role as a Starfighter, Alex returns home only to confront assassins sent by Xur to eliminate him. Realizing the danger he is in, he knows the only way to ensure his safety is to board the Gunstar and fight alongside the friendly alien navigator Grig, portrayed by Dan O'Herlihy. As plans unspool and battles rage, Alex must harness his skills, mastering the advanced Gunstar equipped with a task termed the Death Blossom to clinch victory against the Ko-Dan Armada.
Back on Earth, the android Beta attempts to navigate human relationships, particularly with Maggie, leading to a chaotic face-off against yet another assassin. Meanwhile, Alex and Grig orchestrate a stunning battle maneuver to counter the Ko-Dan’s offensive, turning Alex's arcade strategies into reality, showcasing his growth from a skilled gamer to a commander in the intergalactic battlefield.
As the climax unfolds, Alex’s determination shines through when he sacrifices his safety for victory, culminating in an explosive showdown and the eventual destruction of the Ko-Dan command ship. Despite emerging as the hero of Rylos, he realizes that his journey is far from over. With the threat of Xur still looming, Alex decides to stay in Rylos to strengthen his allies and build a defense against future encroachments.
In a triumphant return to Earth, Alex lands his Gunstar back at the trailer park, where Grig congratulates him on his heroics. He informs his family and friends about his continued commitment to the Starfighter mission and extends an invitation to Maggie to join him in space. With her grandmother's blessing, she chooses to accompany him, while young Louis gets inspired to follow in Alex's footsteps, hinting at a legacy that may one day lead him to preserve their world too.
