The module is set in Forgotten Realms, in Cormyr. The player character returns home and discovers a massacre and sets out for vengeance. The premium module includes many new features:
Horse-riding: ability to use various horses, fight while on horse, and participate in jousting tournaments.
New tilesets and locations comparable to Neverwinter Nights 2.
New medieval knight-styled armor, weapons, and items.
New prestige class "Purple Dragon Knight".
Mini-games including darts, archery competition, "recognize a spell", and jousting tournaments.
Source: Wikipedia, "Neverwinter Nights: Wyvern Crown of Cormyr (module)", available under the CC-BY-SA License.