From the publisher's website:
This 64-page book explores one of the Inner Sea region's most notorious realms—the pirate isles known as the Shackles. Here, pirates from throughout the region congregate, yet not all of the Shackles isles are civilized, even by buccaneers and freebooters. Some hold ancient cyclopean ruins and lost treasures, while others are infested with horrific monsters and savage beasts. Isles of the Shackles explores these islands, providing dozens of interesting and exciting sites for adventures and makes a perfect companion volume for GMs seeking to expand their experience running the “Skull & Shackles” adventure path. A large bestiary containing numerous beasts and filthy pirate villains completes this invaluable addition to any piracy-themed campaign.