So, I am doing the Hunting the Monster quest for Gunmar, and my vampire target that I am to kill is on Solsteim in Hrodulf's House. I had no idea where Hodulf's House is and it was not coming up on my map, so off to the wiki I go and lo and behold it is on Solstheim...

I had no idea that radiant quests from Dawnguard could take you to a location from Dragonborn...