The Elder Scrolls IV: Knights of the Nine

The Knights of the Nine is the first major plugin released by Bethesda Softworks for The Elder Scrolls IV: Oblivion.  Unlike many of Bethesda's add-ons for earlier games, which were large expansion packs that took place away from the world of the base game, Knights of the Nine is much smaller in scope, providing ten or so new quests into the existing lands of Cyrodiil.  In this way, it is very similar to various guild sidequests found in Oblivion.

Upon installing Knights of the Nine, the player hears rumors of an attack on the church in the town of Anvil.  After visiting the Prophet, who tells tale of the second coming of the evil Umaril, the player must reform the order of the Knights of the Nine and search for the lost Crusader's Relics before finally taking on Umaril himself.

Besides the new quests, Knights of the Nine also adds new Ayleid ruins, forts, and caves, as well as the Priory of the Nine, which becomes the knights' base of operations.  Minor changes are also made to a few existing locations, such as the aforementioned ruined Anvil Chapel.  Additionally, several new enemies and items are added to the game, which the player can then use throughout the rest of Oblivion.

Originally, Knights of the Nine was available as downloadable content from Bethesda's website, as well as on the Xbox Live Marketplace.  Additionally, it was available on a retail disc that also included seven of the other eight official plug-ins (the Fighter's Stronghold is not included).  Later, Knights of the Nine was included along with the Shivering Islands retail box, as well as included in the Game Of The Year edition of Oblivion.  As the PS3 version of Oblivion was released later than the PC and 360 versions, Knights of the Nine was included on the Oblivion game disc.