The story follows the adventures of three English people: Humphrey Arbuthnot, his friend and physician, Dr. Jameson, and a woman named Vita, who is also Humphrey's love interest. The novel begins with Humphrey, Dr. Jameson, and Vita setting sail on a yacht, the "e;Ladybird,"e; from the coast of Africa. They are caught in a violent storm and are washed up on the shores of a strange and remote island. There they discover a race of people who are unlike any they have ever encountered. These people are the survivors of a lost civilization, and they possess advanced technology and knowledge that is beyond anything the English travelers have ever seen.