A young boy builds a sand castle on the beach and a dragon moves in. The boy and the dragon spend the day at the shore flying a kite, braving the waves, defying bullies, and roasting marshmallows, while the boy's parents remain occupied nearby with their own pastimes. When no one believes the boy's story about the dragon, the creature launches into a mischievous mode and wreaks havoc on everything in its path-- or is it all in the boy's imagination?