One night, after thinking it over for some time, Harold decided to go for a walk in the moonlight. So begins this gentle story that shows just how far your imagination can take you. Armed only with an oversized purple crayon, young Harold draws himself a landscape full of beauty and excitement. But this is no hare-brained, impulsive flight of fantasy. Cherubic, round-headed Harold conducts his adventure with the utmost prudence, letting his imagination run free, but keeping his wits about him all the while. He takes the necessary purple-crayon precautions: drawing landmarks to ensure he won't get lost; sketching a boat when he finds himself in deep water; and creating a purple pie picnic when he feels the first pangs of hunger.