In the vibrant town of Swellview, a team of scientists working at Evil Science Corp successfully develop an innovative device known as the Reality Altering Device (R.A.D.). During its transport to a highly secure vault, security lapses occur when the guards overlook a strategic placement of a Kid Danger toy in a nearby window, which sets off a chain of unexpected events. Almost immediately after the R.A.D. is secured, an infiltrator disguised as Kid Danger—Jace Norman—steals the device. The thief, Missy Martin, a dedicated fan of Kid Danger and someone who deeply admires the superhero, expertly evades guards and disables them to escape with the R.A.D. in hand.
Back at her home, decorated with memorabilia of the superhero, Missy prepares to use the device to resurrect Kid Danger, unaware that in reality, Henry Hart (/actor/jace-norman) had faked his death to start a new life in Dystopia. There, he fights crime alongside Jasper Dunlop (/actor/sean-ryan-fox), a young hero with unusual skills like fighting in his sleep and speaking Spanish, which makes him a formidable ally. Henry’s decision to leave his former life is kept secret, and he hopes to stay hidden from his past enemies.
Meanwhile, in Dystopia, Jasper reassures Detective Jones that Henry is on his way, attempting to flirt with her despite the tension. Their visit is interrupted when Piper Hart (/actor/ella-anderson) and Schwoz Schwartz (/actor/michael-d-cohen) arrive, visiting to support Henry after Charlotte Page’s departure to Harvard. Jasper, eager to prove himself, warns that a looming threat from the supervillain Blackout (/actor/eric-mazimpaka) is imminent. Blackout’s plan involves stealing plutonium from a truck to destroy Dystopia’s nuclear core, which prompts Henry to abandon a public event to intervene.
Using surveillance hacks, Schwoz tracks the truck’s location, and Jasper fights Blackout in a tense alley battle with his techno-band. Henry arrives just in time to confront Blackout, engaging in a fierce fight and ultimately defeating the villain in front of an audience, gaining cheers from fans. However, their victory is marred by a heated argument over recognition, causing friction between Henry and Jasper, which strains their friendship.
Back at his building, Henry notices Blackout has vandalized his posters, further escalating his frustrations. Meanwhile, Missy activates the R.A.D., which unexpectedly brings her fan-fiction—The Adventures of Kid Danger & Superfan—to life. Henry finds himself transported into Missy’s room, where he wears an upgraded Kid Danger suit. Confused and overwhelmed, he questions her motives, and she reveals her deep desire to bring him back to fight crime once again, motivated by a traumatic mugging incident that left her inspired. Henry, however, confesses that he had faked his death to pursue a peaceful life in Dystopia, leading her to be both shocked and excited by the revelation. Despite her pleas to team up, Henry insists on returning to Dystopia, focusing on his mission there.
The story takes a wild turn when a fictional villain from Missy’s fan-fiction, Coach Cregg, appears and attacks a woman, forcing Henry into action. Unfortunately, Missy’s fan-fiction has altered his abilities, making him more vulnerable. She helps him using the R.A.D., but the situation quickly escalates as Vampiper, a vampiric, electrokinetic version of Missy—a twisted creation born from her being kicked out of the fan club—arrives seeking the device. They narrowly escape, ending up in an '80s-themed nightclub where they meet alternate versions of characters including Frankini and Captain 'Stache.
Henry soon learns that the R.A.D. has entered "story mode," forcing them through various fan-fiction realities to escape. In one dystopian scene, they team up with a survivalist Jasper to fend off Mounties, reinforcing Henry’s appreciation for his true friends. Their quest leads them to Post-Apocalyptic Schwoz, who tells them they need a crystal held by Vampiper to restore their original reality. In the process, Missy blames herself for the chaos but finds renewed hope thanks to Henry’s encouragement, galvanizing her to keep fighting.
Vampiper, now holding Missy’s sister Gemma hostage, creates a dire situation. Henry and Missy stage a daring rescue, though Coach Cregg manages to incapacitate them temporarily with his whistle. During the chaos, Missy sacrifices herself to secure the crystal, urging Henry to complete their mission. They face off against Vampiper and her allies, including Fangkini (/actor/frankie-grande), who arrives to make things more complicated. Henry manages to pass the crystal to Schwoz, who works to restore reality by inserting it into the R.A.D. amidst the final battle.
Thanks to teamwork and determination, the heroes defeat Vampiper and reassemble their broken world, restoring order and reversing the chaos. As the realities collapse back into place, Henry and Missy share a moment of reconciliation, with Henry acknowledging her bravery and growth throughout the ordeal. When they return to their respective worlds, Henry gains a newfound appreciation for his friends, especially Jasper. Missy, inspired by her experience, vows to continue her efforts fighting crime in Newtown.
Later, Henry and Jasper are praised for their victory over Blackout, with Henry encouraging Missy to become his sidekick. They head to their new headquarters, ready for more adventures. The story concludes with Henry visiting a crime scene alongside Captain Man (/actor/cooper-barnes), who is battling drones, highlighting that their crime-fighting days are far from over.
Throughout the credits, viewers see an alternate version of Frankini performing in the ‘80s nightclub scene, hinting at the multiverse of fan-fiction realities that Henry and Missy explored during their wild adventure.
