Mysteries of the Moonsea offers an in-depth look at one of the most important regions of the Forgotten Realms. The Moonsea region is full of wealth and peril. It is home to the nefarious Zhentil Keep, the merchant city of Melvaunt, and the mysterious Irongfang Keep. Mysteries of the Moonsea includes a history of the region, detailed information on the major towns and adventure locations, the important figures and groups that operate in and around the Moonsea, new spells and monsters specific to the area, and tips for Dungeon Masters on running a campaign set in the region.