Three shipwrecked boys make a prolonged stay on a remote coral island in the South Pacific and survive by improvising shelters, finding food, and coping with storms and illness. Their island life is punctuated by encounters with visiting islanders and hostile outsiders, leading to episodes of conflict, daring rescues, and practical ingenuity. Interwoven with action are moral reflections and explicit Christian instruction that stress self-reliance, courage, duty, and a Victorian perspective on order and cultural contrast.