Joe already feels like he's on an adventure when his family moves to a new home. But when he discovers a hidden portal in his closet that leads him to a magical amusement park, he can't believe his luck.

While exploring the magical park, Joe finds the caretaker, Mr. Phelps, who tells him that there's just one rule - never stay in the park until dark or he'll be trapped here forever.

Joe tells his new best friend Sam about his secret, and together they have fun exploring the park and riding the rides until one day when they venture too far into the park and fail to exit before it gets dark.

Trapped in the park, the boys must fight the park's magic spell to try and find a way back home before they're trapped in this hidden world forever.