The key required to leave the shack is received after completing 'With Friends Like These.' or ' Destroy the Dark Brotherhood!.' The Dragonborn is taken here by Astrid after completing the ' Innocence Lost' quest and receiving a Mysterious Note from a courier. The shack is inaccessible from the outside before starting the quest ' With Friends Like These.,' as the key is needed to enter the shack. It is an old, desolate house coated with blood.
