On a quiet day, near the Caribbean island of Black Conch, a mermaid raises her barnacled head from the flat grey sea. She is attracted by David, a fisherman waiting for a catch, singing to himself with his guitar. Aycayia the mermaid has been living in the vast ocean all alone for centuries.

When Aycayia is caught and dragged ashore by American tourists, David rescues her with the aim of putting her back in the ocean. But it is soon clear that the mermaid is already transforming into a woman.

This is the story of their love affair, of an island and of the great wide sea.