Protagonists Hal and Roger Hunt are the sons of animal collector John Hunt; they have taken a year off school to help capture animals for their father's collection on
Long Island, New York, after which the captive specimens are sold to zoos, circuses and safari parks. In
Amazon Adventure, the boys' literary debut, Hal is 18 years old and Roger is 13 years old. Hal is the typical hero: tall, handsome, and muscular, possessing an almost limitless knowledge of natural history and a caring and trusting disposition. Roger, on the other hand, is an ardent practical joker, often mischievous and cheeky but just as resilient and resourceful as his older brother — sometimes even more resourceful.
Supporting characters Hal and Roger are aided by many characters in their adventures, some of whom reappear in subsequent books. Their father John Hunt personally leads the expeditions in Amazon Adventure and African Adventure. In the South Seas the brothers are accompanied by the
World War II veteran skipper Captain Ike and his trusted crewman Omo. The African safari team comprising Joro the tracker, Toto the gun bearer, Mali, and Zulu the
German Shepherd dog had the most frequent appearances. As a former member of the
cannibalistic Leopard Society, Joro is the only reformed antagonist who appears in more than one book.
Villains Each novel in the
Adventure series is notable for its memorable selection of loathsome villains and enemies. Some of these, through their interactions with Hal and Roger, are led to redeem their past misdeeds, while others simply suffer the consequences of their actions. Only one character, the cunning "Reverend" Merlin Kaggs, appears as a villain in more than one book. ==Revival==