You may notice the road that seems to lead away from the front of the building- this cobble path does not lead to the Bloodlet Throne from a more convenient direction, though. Instead, it is the route from the Bloodlet Throne to large impassable gate in the Southern mountain range.
Curiously, in addition to the slightly distressing blood spatters on the lintel, there is also a wood chopping block right outside of the door to Bloodlet Throne.
On entering, you will find yourself in a cold, dank front hall that is semi-adequately lit by a couple of torches in the hallway leading further in. Be wary of the floor approaching the hall- a pressure plate here will trigger a pair of flame-spewing traps in the walls, and you could easily find yourself accidentally charbroiled.
Pass these and their accompanying impaled skulls to enter a curious U-shaped room. Proceed with caution here, as the middle of the room has a large barred window that looks down into the next area of the dungeon. You should be able to see one clear spellcaster and one clear warrior through the barred opening- a vampire and her thrall.
Cautious observation will also let you note the two hanging lanterns here, and the fact that the nearer one is not only over one of the points that the two in the room below patrol, but is also over a rather large pool of oil. If you'd like to make things a little easier on yourself (and if you're trying to avoid getting turned into a vampire, there's every reason to) you can time a bowshot between bars so as to set the two on fire.
Thankfully, handling them is easy- the fledgling vampire can take very little damage, so it's mostly a melee fight with her thrall after you've flattened her. While there is little of value lying around, you can loot their corpses, and then take a moment to look around the room. There is a wooden door, behind which lupine howling can regularly be heard, and there is also a route deeper into the Bloodlet Throne underneath the room through which you entered.