With its suspense, its ambiguities, and its hidden identities, the novel is clearly in the tradition of the spy novel. By using those techniques to question more abstract questions such as the nature of love or human loyalty, Greene is closer to Joseph Conrad than to most espionage novelists. Oddly, however, with its basic plot of a young English boy wishing to run away from the dull existence of everyday life to find a foster father who can show him a life of adventure, and perhaps a fortune, the book is an adult's version of Robert Louis Stevenson's Treasure Island. Greene himself makes that clear by his references to Sir Francis Drake, Captain Morgan, and the English pirates of the Caribbean.