Jim Spencer is marooned on an enchanted island. He lives in the company of an undine, a dryad and a sylph. Spencer falls in love with Celia, the mermaid. She offers him treasures if he leaves her, because the price for their love will be her becoming human. Spencer chooses Celia and they live happily ever after. The dryad and the sylph explain that everything has been a masquerade to shock Celia out of believing she is an undine.