Kill the hagraven and its familiar in the first room to obtain the [[Skyrim:Keys#Ravenscar Hallow Cage Key|Ravenscar Hallow Cage Key]]. Flip the lever near the hagraven's tent to open a secret wall. Free the imprisoned bandit using the hagraven's key or your lockpicking skills if you didn't pick it up. He will help you fight the remaining two hagravens before turning on you.
There are some [[Skyrim:Potions|potions]] and [[Skyrim:Gems|gems]] on the table as you enter the secret passage. Dead bandits and a dead [[Skyrim:Spriggan|Spriggan]] are located just past the first two cages. In the north-west part of the room, a copy of the [[Skyrim:Destruction|Destruction]] skill book ''[[Skyrim:The Art of War Magic|The Art of War Magic]]'' can be found on a table next to a chest. A third dead body can be found in a locked cage past the chest, at the far end of the room.