Ten-year-old Portia Bennett and her friend Jason continue to search Toronto for clues to the origin of the purple monster, Jellaby--but things turn dangerous when they are confronted with a tentacled monster with a taste for children.

Portia is bright beyond her years, which means it difficult to make friends in her new school, and her single mother is preoccupied, so when Portia sneaks into the woods after midnight and discovers a shy and sweet purple monster, she is delighted by her new friend--but Jellaby has secrets of his own.