This quest is not available in game.
Kill Stalvan Mistmantle and show Madame Eva his family ring.
Stalvan Mistmantle led a life of depravity. Innocent victims died by his hand. Undoubtedly he is guilty of countless crimes. Now the lunatic threatens Darkshire. The Light only knows what sordid acts he is plotting. Travel to his cottage just north of town, <Class>, and execute Stalvan, once and for all.
When the deed is done, travel to Madame Eva's and show her his family ring. After all, it was her premonition that led to this gruesome discovery. But Darkshire is safer because of her.