In pursuance of his theory that the ideal manner of raising children is to keep them apart from the world, Professor Landor, a widower with two children, Helene and Achilles, purchases Arcadia Island, in an unfrequented section of the country. There, with the aid of his friend, Professor Reichhart and Norah, a nurse, he rears the children. Helene is his own child but Achilles is a foundling whom the professor has adopted. When the children are grown, the isolation of the island palls upon them, particularly when Norah, who has discovered a small treasure, fills them with a craving to see the wonderful outside world. Aided by her, they build a raft and escape from the island. Nora dies from the shock of their perilous trip to the mainland during a terrible storm, and the two children are left alone in the world. On landing, they run into a party of young society people out picnicking. Marion Warner, the leading spirit of the party, suggests they show the two unsophisticated strangers something of the world and its pleasures. They create much amusement in their new surroundings by their awkwardness and unconventionality. Society takes them up and for a while, the two are in love with the world. They soon tire, however, and when Helene sees Achilles in the arms of Marion, she receives a rude awakening. Longing to be again in quiet Arcadia, she runs away. Achilles frantically follows her, leaving Marion without a thought, and seeing her in a boat going towards Arcadia Island, plunges into the water and swims after her. He is nearly drowned, but is found later by Helene, cast up on the beach of the island. She succeeds in restoring him to consciousness, and deciding that in Arcadia only is perfect happiness and contentment to be found, the two hand-in-hand, stroll back to the little cottage where the lonely old professors are anxiously awaiting them.