Each night, when Ben falls asleep, his Crayons' magical Crayon Box transports them to Color City, a world of dazzling hues, soaring fantasy and the whimsy of childhood. When Yellow is accidentally left behind in Ben's room, she awakens two Unfinished Drawings: King Scrawl, a huge monster, and Gnat, Scrawl's sidekick. They follow Yellow to Color City and claim the enchanted Rainbow Waterfall and its color for themselves. Soon Color City will fade and the lovable crayon characters will disappear. It's up to Yellow and her pals to save the day. Meeting with fantastical creatures and fun adventures along the way, Yellow discovers she has more courage than she knew and learns to believe in herself and to count on the support of her friends.