The hidden room can be reached by opening the moveable panel in the back of the closet in the room to the right (possibly Delphine's), of the bar in the Sleeping Giant Inn. Once the panel has been moved, which will only occur by starting the quest "A Blade in the Dark" and being invited in by Delphine, Delphine's Secret Room may be entered. Once the Dragonborn talks to Delphine, they are able to take anything in the room.
On very rare occasions, when searching through the secret room a long time after cleaning it out of its possessions, a bug may occur where when looking through the chest it holds a duplicate of every single item in your inventory letting you have double of everything you have.[confirmation needed]