Ten-year-old Ben Silverstein arrives in the tiny town of Buttonville expecting a dull summer with his grandfather. Everything changes when a wounded baby dragon appears and leads Ben and local girl Pearl Petal to Dr. Woo's Worm Hospital — a veterinary clinic secretly treating sasquatches, lake monsters, unicorns, and griffins. The two children become apprentices, sworn to keep the Imaginary World a secret.

Ben Silverstein is a clever city kid who quickly sheds his skepticism to become a brave apprentice. Pearl Petal, Buttonville-born and fearless, balances Ben's caution with bold action. Together they grow from startled bystanders into genuine protectors of the Imaginary World.

Across six books, Ben and Pearl navigate increasingly dangerous rescues in Buttonville and the Imaginary World beyond a hidden portal. Their bond deepens as they outwit the ruthless poacher Maximus Steele, who threatens every creature they love. The series builds to a thrilling finale involving a swarm of sugar fairies and Steele's ultimate defeat.