On Halloween Eve at Mossy Bottom Farm, excitement turns to dismay when the clumsy Farmer ruins the pumpkin patch. Shaun tries fixing it with science experiments, but things go wrong when a wild beast appears in the woods.

The Paw Patrol lands on a mysterious dinosaur island after a storm, where they meet Rex, a stranded pup. When Humdinger's reckless mining triggers a volcano, the team faces their biggest rescue mission yet to save the island.