Neverwinter Nights 2: Storm of Zehir is an expansion pack for the computer role-playing game Neverwinter Nights 2, developed by Obsidian Entertainment and published by Atari. It was released in late 2008 in North America, Europe, and Australia. Like previous entries in the Neverwinter Nights series, Storm of Zehir is based on the paper and pencil fantasy role-playing game Dungeons & Dragons, and uses the game's 3.5 edition ruleset.
Storm of Zehir was inspired by older computer games like the Baldur's Gate and Icewind Dale franchises. The storyline foreshadows the events of the fourth edition of Dungeons & Dragons and follows the adventures of a group of merchants in the Samarach and Sword Coast areas of the Forgotten Realms campaign setting.
Source: Wikipedia, "http://en.wikipedia.org/wiki/Neverwinter_Nights_2:_Storm_of_Zehir," available under the CC-BY-SA License.