This quest is initiated by reading "The Journal of the Sun Wolf". This item is dropped on monsters in The Peat Bog (Bog Slugs, Rot Crawlers, Mist Wolves and Bog Faeries confirmed). It requires you to explore a few locations in the Peat Bog:
After finding Deadend Niche The Sun-Wolf will spawn. The quest completes when he spawns. You can kill him or flee.