The Dawnguard is an organization dedicated to hunting vampires who attempt to stop the return of a powerful clan of Vampires named the Volkihar who possess the power to turn into monstrous "vampire lords". The Volkihar's leader Lord Harkon intends to use an Elder Scroll to permanently blot out the sun. The player can choose to either aid the Dawnguard or join the Volkihar, becoming a vampire lord themselves in the process.