When Sam and Rosie's grandparents give them a trip to a dude ranch for their Christmas present, they're not sure what to expect, but they're eager to explore! They think it will be even more fun to bring their friend Izzy along . . . only to discover that she's not quite as good a friend as they originally thought.

Though they enjoy bonding with the horses on the ranch, and meeting Chief Growling Bear, Sam and Rosie are frustrated by Izzy's behavior. Even so, when Izzy gets attacked by a werewolf, the siblings know they need to help protect her, each other, and the horses at the ranch at all costs. The children must remain on their guard and work together to face the werewolves and to protect Izzy, despite how rudely she's been acting. Fortunately, Malcolm Marpole and Chief Growling Bear are there to help them.

Thunder and the Werewolves showcases caring for animals, working as a team, and learning respect for others. When we work together, we can face and overcome almost any danger.