In an oceanic realm littered with magic, Crescent Isle had always been sheltered off from the remainder of the world for an odd reason. It was as though a giant dome had harboured peace and prosperity on the island for aeons on end. However, with the destruction of the First Seal, darkness rises to, once again, dwell within the depths. Pirates, eyes glued onto to island's wealth and riches, invade the island's capital city: Silvermoon Wharf.
Overwhelmed by the outlaw forces, the island's meagre defences stand no chance and hope is seemingly lost. Had it not been for a mysterious old man, chaos would have ensued further.
Intrigued by this unsung hero, Cynthia Adams sets out to meet the individual face to face - only to receive a peculiar medallion from the island's obscure saviour, along with the request to restore the distorted balance between light and darkness. All of a sudden exposed to the entirety of the Thirteenth Sea, Cynthia heads down the rocky path of realisation as she comes to terms with the horrifying state of global unrest.