From the back of the book:
A strange vessel has crash-landed on the island of Gundarlun, while the Sword Coast is being plundered by pirates. Are the two events linked?
While the cities of the Sword Coast try to defend themselves from raiding buccaneers, bloodthirsty sea devils and piscine mutants, the characters try to join the dots, and uncover what's occurring beneath the Trackless Sea.
The adventurers must investigate the Kraken Society, take on the notorious Sea King Tentrix, and discover what lairs in the Ruins of Ascarle.