Dark Ancestor

Walkthrough
After the Dragonborn has helped Dengeir by stealing a letter from Lod, Dengeir then decides to entrust the Dragonborn with a more important task. The old man mentions that one of his ancestors, Vighar, is a vampire and that it was his duty to make sure that the vampire remained in his grave. However, Vighar has escaped.

Dengeir tells the Dragonborn that he is now holed up at Bloodlet Throne.

Destroy the vampire Vighar
The Dragonborn must then travel to Bloodlet Throne and kill Vighar, who has now gathered several thralls to help him out.

Tell Dengeir that Vighar is dead
Once the vampire is dead, return to Dengeir and inform him. Dunkler Vorfahr