The story takes place in the mid-19th century in a remote settlement of Queensland, Australia. One day as a group of children are playing at the edge of the village, a remarkable figure stumbles out of the bush. This dark, unkempt person (Gemmy) turns out to be a white man who fell from a ship 16 years earlier (when he was a 19 year old sailor) and has lived with an aboriginal tribe ever since. He hardly remembers English, and his culture and sensibility have become those of his adopted people.

At first Gemmy creates a sensation in the settlement and people want to help him, despite his obvious savage mentality (after all, he isn't even embarrassed by nakedness!). He goes to live with the McIvor family, whose daughter, Janet, and nephew, Lachlan Beattie, were among the children who found him. While Mrs. McIvor accepts Gemmy with Christian love, her husband Jock is skeptical.

In fact, it soon becomes clear that there are major tensions in the village regarding Gemmy. Has he really become "one of them" (a black)? Can he be trusted? He seems harmless enough--almost a pleasant imbecile--but perhaps it is all a subterfuge. Perhaps he is in contact with THEM.

Among the European settlers, there are two views of how to handle the blacks. One group believes they should simply be wiped out--every one of them killed--because they are savage, worthless, and couldn't possibly become (real) Christians. A second group has a more romantic view. They think the black people could be "tamed" and become their servants. They envision themselves as owners of large plantations (as in the southern United States) worked by multitudes of happy and harmless black servants.

Representatives of both groups try to win Gemmy's confidence and obtain information regarding the whereabouts and plans of the black tribes. He, however, remains silent about these matters, although pleasant and deferential toward everyone. An uneasy truce holds until one day two aboriginal people are observed visiting with Gemmy on McIvor's property. This creates an uproar, which eventually leads some of the God-fearing whites to commit acts of vandalism and to injure Gemmy.

To preserve the peace, the McIvors send Gemmy to live with Mrs. Hutchence, an eccentric woman who lives on the margin of the settlement. However, he soon disappears into the wilderness, but not until he retrieves--and destroys--what he thinks are the seven pieces of paper on which Mr. Frazier, the minister, had written Gemmy's life story soon after he had emerged from the bush.