It is an old, desolate house. The shack is inaccessible from the outside before starting the quest "With Friends Like These...," as the key is needed to enter the shack.
The Dragonborn is taken here by Astrid after completing the "Innocence Lost" quest and receiving a Mysterious Note from a courier. The key required to leave the shack is received after completing "With Friends Like These..." or "Destroy the Dark Brotherhood!."
Alternately, attacking Astrid instead of killing a victim will initiate the quest "Destroy the Dark Brotherhood!"
- Should one return to the shack at any time, the surviving NPCs will still be there.
- Items stored in the chest and drawers are not safe for storage and will respawn after a few days.
- The shack looks to have been occupied at a not too distant date; there is a fire in the grate, and table and chairs set up. However, the fresh bloodstains on the walls and floor suggest that whomever lived there was killed quite recently.
- Using PC commands to unlock the door, the Dragonborn can enter the shack and Astrid and the three hostages will be inside. They can then start either quest without having to do the earlier quests.