The narrator, a scientist, recounts searching for his younger brother, a devoted musician long thought lost at sea, and the voyage that led him to an uninhabited island. After a mutiny leaves the narrator cast off in a small boat, he is shipwrecked and discovers his brother living alone on the shore, physically altered, feral in appearance but tender in manner. The reunion prompts a gradual revelation of how solitude, music, and survival have reshaped the brother's mind and life. The account interweaves shipboard danger, island hardship, and philosophical reflections on art, loneliness, and human transformation.