Follows the adventures of a group of neighborhood children who create costumes from cardboard and use their imagination in adventures with knights, robots, and monsters.

The kids of the Cardboard Kingdom go on a new adventure! This time, they are in search of new friends-- but what they discover is a lot more like enemies... It’s winter break in the Cardboard Kingdom, and kids from the town across the park want to play together! But according to the evil Sorceress, not just anyone can join the kingdom... So it’s not long before the two communities spiral into battle. Will the Sorceress realize the error of her ways before all hope is lost? Will friendship still manage to win the day?

When a mysterious monster wreaks havoc in their neighborhood, the newly minted Monster Mashers will go to any lengths to protect the Cardboard Kingdom and solve this mystery.