When their grandfather buys a bookstore at auction in New Orleans, the Alden children help clean it up and discover that several people seem to be obsessed with the store and its contents.
A young boy relates his adventures during the year he spends living alone in the Catskill Mountains, including his struggle for survival, his dependence on nature, his animal friends, and his ultimate realization that he needs human companionship.
Through a series of letters a boy, his parents, and others discuss Camp Wannaleavee, the camp bully, and Plantzilla, who has been forbidden to come but misses his caretaker and arrives in time to become the camp hero.