Summary: A king emerges from a hidden door in a city park, startling two children sheltering from the rain. No sooner does he push a map and some strange objects into their hands than he is captured by hostile forces that whisk him back through the enchanted door. Just like that, the children are caught up in a quest to rescue the king and his kingdom from darkness, while illuminating the farthest reaches of their imagination. Colored markers in hand, they make their own way through the portal, under the sea, through a tropical paradise, over a perilous bridge, and high in the air with the help of a winged friend.