4 Ladies In The Red Lantern
Once you pass through the door with the 6 digit code, you will come to 4 ladies. 1st you must go back to Mia's apartment to get the 2nd half of the apple. Then when you are ready with all 4 of the items you need; the mask, the nail, the apple and the rose. Place them in this order. Mask, apple, rose and then nail and the secret door will open. You must talk to Mia and get the keys to her apartment.