Shaggy Rogers [Matthew Lillard] and his dog Scooby-Doo [Frank Welker] crush the hardest level of WWE's latest video game, earning an all-expenses-paid stay at WWE City to watch WrestleMania. At their insistence, their friends Fred Jones [Frank Welker], Daphne Blake [Grey DeLisle], and Velma Dinkley [Mindy Cohn] accompany them, turning a simple gaming win into a full-blown, mystery-brimming trip. Upon arrival, the gang meet John Cena [John Cena], who welcomes them with VIP tickets for the weekend; his trainer Cookie [Charles S. Dutton] and Cookie's nephew Ruben [Bumper Robinson] also join, adding backstage color and flavor to the adventures ahead.
As the show gets underway, Mr. McMahon [Vince McMahon] unveils the WWE Championship belt, a title that had been vacated after Kane's [Glenn Jacobs] prior match was overturned. The belt is up for grabs over the weekend, promising bold rivalries and dramatic moments while hinting at a hidden threat looming behind the spectacle. That night, Daphne and Velma overhear Ruben and Cookie arguing about Cookie never making it as a WWE wrestler due to a lingering leg injury, exposing tensions behind the glitz and glamour of WrestleMania.
Meanwhile, Shaggy and Scooby are assaulted by a spectral “Ghost Bear.” Triple H [Paul Levesque] and Brodus Clay [George Murdoch] intervene, but the monster overpowers them before vanishing again. The following morning, Mystery Inc. learns from Ms. Richards [Mary McCormack] that the Ghost Bear has been terrorizing WWE City for weeks. Cena and Cara explain that the Ghost Bear’s origin stretches back over a century to a bear named Vicious, defeated by Sin Cara Grande on the land that would become WWE City; Vicious’ spirit was stirred by WrestleMania and now seeks revenge.
The plot thickens when Scooby is caught stealing the WWE belt, though Velma proves he was hypnotized at the time, while Ruben deduces that the video game contains flashing lights that implant post-hypnotic suggestions. Despite these explanations, McMahon offers Scooby and Shaggy a chance at freedom if they can defeat Kane [Kane] at WrestleMania. With Cookie and AJ Lee [April Jeanette Mendez]’s help, the duo undergo a crash course in wrestling, learning the basics, timing, and teamwork needed to face their formidable challenge.
Meanwhile, the rest of Mystery Inc. investigates the cave where Vicious was banished, uncovering a hidden room filled with hypnosis books, schematics for an EMP device, and a calendar that confirms the plan to target WrestleMania. A hurricane of events erupts as the Ghost Bear attacks the arena; Cena fights it off, while the underground generator is knocked out by the EMP. The arena lights flare with pyro as Scooby and Kane continue their clash, and the Ghost Bear finally charges the ring. In a dramatic unmasking, the team realizes the culprit is Cookie, who reveals a long-held dream of undermining WWE loyalty and glory by using an exosuit built specifically for this plot.
Cookie is arrested, and Cena recovers the real WWE belt. Mr. McMahon finalizes Ruben’s place on the WWE roster, then awards the belt to Scooby-Doo and Shaggy, crowning their unlikely victory and closing a weekend that blended mystery, humor, and high-octane wrestling into one unforgettable adventure.
