Neverwinter Nights 2: Mysteries of Westgate is an add-on for Neverwinter Nights 2. It introduces no new game elements but tells its own story: The player character, an adventurer, found a mysterious mask during his travels. But since he picked the mask up it causes him physical pain and nightmares. To uncover the secret behind the mask he travels to Westgate, where the game begins.
The whole game plays within this city, more exactly its three main districts and underground areas. During the game the player has to associate with one of two factions: the crime organization Ebon Claws or the Church of Lathander. Besides its story, the game also features three companions, four new monsters and a new sewer tile set.