The narrative follows Ned Rogers, an orphaned boy who leaves home to seek work and adventure, eventually joining a sea voyage that leads to shipwreck and marooning on a remote island. Stranded with companions, he uncovers clues to buried treasure and confronts dangers including storms, wrecked vessels, mysterious visitors, rising suspicions among crewmates, and imprisonment. The survivors make repeated efforts to reach port, encounter Havana and other stops, and after trials and narrow escapes they resolve the island mystery and recover their prize.