At the location of Charles Bay in Deathloop, at night, go left to the fortress. Go to the territory, behind the high walls, and climb the cornice on the right, to the open window. Defuse the red trap and go into the room. Blue rays will hit you and the lock will break. It’s OK.
Read the note on the floor under the door. You can read the note on the table. You will recognize the code. Come back in the afternoon the next day with an offset. Carefully open the door and teleport to the castle past the blue and red rays. Enter the code and meet Peak Resley. However, the girl will not offer you anything special, except for a conversation.