The game begins with Nowe becoming a fully-fledged Knight of the Seal. During his first mission, Nowe begins to doubt the ethics of the Knights' methods, as the seals require human sacrifices to remain strong. During a second mission to ensure the protection of the seal in the District of Soul Flame, Nowe encounters Manah, who kills the guardian Zhangpo and destroys the seal. Manah is sentenced to be burnt at the stake, but uses her magic to escape. After returning from the mission, Nowe is poisoned by Gismor, who reveals that he killed Nowe's adoptive father Oror. Surviving and escaping with Legna, Nowe is pursued by the Knights, including Eris, who wishes to persuade him to return.
As with the original Drakengard, the game is split into chapters and subdivided into ground-based and airborne missions. The story of the game dictates which missions come when during the initial playthrough and how they play out, though as the player progresses, new remixed versions of the various playable levels called "free missions" are unlocked, which allow the player to go through the missions with the story elements removed. The player can jump between the game world's self-contained areas via a world map unlocked after the first chapter.
Source: Wikipedia, "Drakengard 2", available under the CC-BY-SA License.