Immaculate, charming, fearless wanderer, Jim Maitland, has a peculiar code of morals and an unforgettable character. Our enthusiastic narrator, Leyton, meets the legendary Maitland on the Island of Tampico - a flawless jewel in a sapphire sea, with more vice than the slums of a city - and leaps at the chance to accompany this charismatic man on his spontaneous travels.

When intrepid adventurer, Jim Maitland, returns to England for a brief visit, he meets a charming young woman named Judy Draycott, who solicits his help in a perilous matter. She relates the story of her brother, Arthur – drifting in South America until he meets an old sailor who, on his deathbed, tells him about a hoard of buried treasure. When Arthur is shot during an attempt to return to London, Maitland persuades his cousin, Percy, to accompany him to Lone Tree Island, where the treasure is allegedly buried. But what can they do with only half a map? And can they evade the undesirables on their trail?