Twins, Lilly and Jimmy find an unusually shaped key

which unlocks the door to a magical castle where they have a fun packed learning adventure. Along the way they have to complete tasks and figure out puzzles. They hear and meet very strange and funny characters that help to guide them along. Lilly and Jimmy forget all about the real world but to their disappointment, they are eventually returned home where they find no time has passed and that they still hold the key.