In 1855 a philanthropic young person, Miss Charlotte Smith, was escorting forty orphans to San Francisco when the ship was wrecked, and the survivors-Miss Smith, the orphans, a doctor, and some others, landed on a desert island. Those sailors who had escaped deserted them the next day in the boats. There they remained unvisited for some seventy years, with little to disturb the monotony beyond the adventures of the Doctor, who was secured in turn by Miss Smith and a shark. All this is contained in chapter one. The second chapter opens in 1922 at Cambridge, where lived the descendants of one of the sailors who deserted-a professor and his three children. A document and chart coming into the professor's hands, left by his dead grandfather, telling the story of the marooning of Miss Smith and the orphans, the professor and his family voyage out to the island and find there a thriving community, and Orphan Island is chiefly concerned with the community and the relations of it to the professor and his family.