Robert J. Kral

After helping WWE solve the mystery of the ghost bear in Scooby-Doo! WrestleMania Mystery, the Mystery Inc. gang is seen at WWE’s latest venture, The Muscle Moto X Off Road Challenge, an off-road racecar race for WWE superstars, with a big cash prize. Scooby-Doo and Shaggy are there working at a food truck. Many WWE superstars are in the race, including WWE chairman Mr. McMahon's own daughter Stephanie McMahon and her husband Triple H. Scooby and Shaggy are excited to hear that The Undertaker is going to be in the race.

Suddenly a demon racer named Inferno appears in a big race to sabotage the race, Mr. McMahon hires Mystery Inc. to solve the mystery. Mr. McMahon wants Stephanie to pull out of the race, but she refuses. After learning they both have wealthy dads, Daphne becomes friends with Stephanie, making Velma feel very left out. The Undertaker is disappointed that his partner, Dusty Rhodes was injured in the race and recruits Shaggy and Scooby to be his new partners under their names "Skinny Man" and "Dead Meat", to which they reluctantly agree to. However, since Undertaker's car was also destroyed in Inferno's attack, Fred modifies Shaggy and Scooby's food truck so they and Undertaker can race that car instead and nicknames it "The Scoobinator".

During the first race, Inferno attacks the racers again and Velma, Daphne and Fred notice that Mr. McMahon is nowhere to be seen. That night Scooby and Shaggy are chased by Inferno only to be saved by The Miz. The following morning, Inferno attacks again and Scooby, Shaggy and The Undertaker almost drown when The Scoobinator lands in water. Luckily, the trio is able to escape. That night, Daphne tells Velma even though she enjoyed hanging out with Stephanie, Velma will always be her best friend. The following day, Fred modifies the Mystery Machine so Scooby, Shaggy and Undertaker can race it in the final race. This time he, Daphne and Velma join the three of them in the car. Sure enough, Inferno attacks once more and goes after the gang. However, the other WWE stars in the race gang up on Inferno and attack his car with theirs.

After an action filled showdown, Inferno is defeated and unmasked to be Triple H. He and Stephanie used the costume to win the race. Stephanie mostly masterminded the plan because she was mad at her father for not letting her get in the race. Mr. McMahon apologizes saying he only wanted her safe, but still allows the police to take Stephanie and Triple H to jail. With Stephanie and Triple H disqualified, Scooby, Shaggy and The Undertaker win the cash prize by default, which they share with Dusty.