From the publisher's website:
The adventurers now have their own island and port, but they’ll need more than one ship to defend it. They must scour the harbors and docks of the Shackles to recruit more ships and more crews to their flag. But when a rival from their past sends a fleet to attack them, they must defend their island home. And when they sail to his island to get their revenge, the adventurers discover a traitor whose betrayal threatens all of the islands of the Shackles.
A Pathfinder Roleplaying Game adventure for 11th-level characters, this volume continues the Skull & Shackles Adventure Path. This volume of Pathfinder Adventure Path also delves into the secrets of the deadly cult of Norgorber, god of thieves and assassins, along with presenting new rules for battles between whole pirate fleets. New monsters from the depths of the sea and exotic islands also fill the Pathfinder Bestiary, while Robin D. Laws (author of the Pathfinder Tales novel The Worldwound Gambit) continues his tale of pirates and lost treasures in the Pathfinder’s Journal.
Each monthly full-color softcover Pathfinder Adventure Path volume contains an in-depth adventure scenario, stats for several new monsters, and support articles meant to give Game Masters additional material to expand their campaign. Pathfinder Adventure Path volumes use the Open Game License and work with both the Pathfinder RPG and the world’s oldest fantasy RPG.