Seven years after the Monsterpocalypse, Joel Dawson, along with the rest of humanity, has been living underground ever since giant creatures took control of the land. After reconnecting over the radio with his high school girlfriend, Aimee, who is now 80 miles away at a coastal colony, Joel begins to fall for her again. As Joel realizes that there's nothing left for him underground, he decides to venture out to Aimee, despite all the dangerous monsters that stand in his way.
Debt collectors French and Sue get to work doing what they do best _ cracking skulls and breaking bones _ as they chase down the various lowlifes who owe money to their boss, Tommy. They're summoned to Las Vegas to collect from a dirty casino owner, who happens to be a vicious ex-lover of Sue's.
Scooby (Frank Welker) and the gang are in Crystal Cove to take part in a parade and also stop a monster called the "Haunted Scarecrow." After capture, the Haunted Scarecrow is revealed to be one of Gotham City's most evil super-villains: Dr. Jonathan Crane.