The entrance is unremarkable. Once inside the lair, the Dragonborn will be greeted by a couple of frostbite spiders. After disposing of the spiders, a passage to the south leads to an open room that offers three paths from which to choose, as well as a Vampire's Thrall to battle. The right and center options are dead ends but offer some loot. The left tunnel leads to a chamber with a hole in the ground and another Vampire's Thrall to fight.
Continuing through another tunnel will take the Dragonborn to Movarth's chamber, where a master vampire or volkihar master vampire is accompanied by two guards. After he has been dispatched, the Dragonborn can continue east up a path that leads to a side chamber that's occupied by a thrall. Behind the thrall is a chest with leveled loot and a bookshelf against the south wall (near the Alchemy Lab) with the book The Aetherium Wars. There is another path to the south that leads to a room with a thrall, an Ancient Vampire, a chest up a wooden ramp to the right (west), and a dirt ramp up to the left (east) that leads through a twisty passage and eventually leads to an opening high above the dead end room to the right from earlier.