After helping WWE solve the mystery of the Ghost Bear in Scooby-Doo! WrestleMania Mystery, the Mystery Inc. gang returns to a new WWE spectacle: the Muscle Moto X Off Road Challenge, a high-stakes off-road race for a massive cash prize. Scooby-Doo and Shaggy Rogers Matthew Lillard are there on the ground, running a food truck that serves up quick bites for the thrill-seekers and competitors, while a chorus of WWE stars lines up for the rugged contest. The energy is electric, and the excitement is matched only by the rumor that The Undertaker Mark Calaway himself might join the lineup.
But the fun takes a sharp turn when a demon racer named Inferno Steve Blum bursts onto the track, sabotaging cars and threatening to derail the entire event. In the chaos, Mr. McMahon Vince McMahon hires Mystery Inc. to get to the bottom of the danger and restore order. Stephanie McMahon Stephanie McMahon is eager to prove herself in the race, and she resists her father’s attempt to pull her out, a decision that strains old alliances and tests loyalties. The tension deepens as Daphne Blake Grey DeLisle befriends Stephanie, while Velma Dinkley Kate Micucci feels increasingly left out as the group dynamics shift around the daughter-and-father clash.
On the track, The Undertaker forms an uneasy alliance with Dusty Rhodes Virgil Runnels, hoping to make a strong run. To keep things interesting, the Undertaker recruits Shaggy and Scooby-Doo to race under the factions’ banner, giving them cunning nicknames—“Skinny Man” and “Dead Meat”—even as they hesitate to trust this odd pairing. When the dust settles after an initial wreck, Fred Jones, with his own instincts, helps reconfigure the plan: after their own car is destroyed, Fred and the gang modify the Mystery Machine so that Scooby and Shaggy can instead drive alongside the Undertaker in a rebuilt setup nicknamed The Scoobinator. The changes bring new energy to the team and a renewed sense of purpose for Mystery Inc.
The first race unfolds with Inferno’s brutal assault continuing to threaten every participant. Velma, Daphne, and Fred notice that Mr. McMahon is conspicuously absent, which raises questions and suspicions about who’s controlling the chaos and why. In a tense moment, Scooby-Doo and Shaggy are chased by Inferno, but they’re saved by none other than The Miz Mike Mizanin, who lends a timely hand and some much-needed bravado to the trio’s precarious situation.
The next morning brings another wave of aggression from Inferno as Scooby, Shaggy, and the Undertaker face a perilous moment on the water when The Scoobinator lands awkwardly and nearly sinks. They manage to escape a close call, reinforcing the fear that Inferno is always one step ahead. Throughout the night, Daphne confides in Velma that while she enjoyed her time with Stephanie, Velma remains her closest friend, a confession that highlights the evolving friendships and the fragile trust within the group.
With renewed resolve, Fred ramps up the engineering, upgrading the Mystery Machine so Scooby, Shaggy, and the Undertaker can take part in the final race in a single, unified vehicle. The rest of the gang joins in, and the final showdown is set. Inferno strikes again, testing the team’s nerve as they push toward the finish line. This time, a broad alliance of WWE stars closes in on Inferno’s car, delivering a coordinated assault that disables the demon-powered vehicle.
In a climactic moment, the Undertaker squares off with Inferno and brings the showdown to a head. The car’s mysterious control system is revealed to be a radio-based signal—Inferno uses the deception to steer the vehicle. Working together, the gang devises a remote-disruption plan to cut the signal, leveling the playing field and exposing the method behind the sabotage. The action explodes in a high-energy sequence that blends the racing spectacle with Mystery Inc.’s signature problem-solving instincts.
The truth comes out in a dramatic unmasking: Inferno is revealed to be Triple H Paul Levesque. Stephanie McMahon masterminded the scheme, using the costume-and-punkish persona to win the race and to settle a personal grudge against her father for not letting her participate fully in the competition. Mr. McMahon apologizes for the missteps and, in a surprising turn, orders law enforcement to take Stephanie and Triple H into custody. With the would-be conspirators disqualified, Scooby-Doo, Shaggy Rogers, and The Undertaker emerge victorious by default, claiming the cash prize as the rightful winners of the event.
In the aftermath, the mystery is resolved, friendships are reaffirmed, and the gang reflects on the lesson that ambition without accountability can twist even a high-profile event into something dangerous. Through cunning, teamwork, and a dash of unlikely collaboration, Mystery Inc. restores order to a weekend that melded the flash of WWE spectacle with a classic Scooby-Doo mystery—and they ride off into the sunset with a sense of closure and a renewed sense of purpose for their next adventure.
