Daughter Dearest

You found yourself outside the main office within the Heat Haze Mansion, home of the "Lamplight" Spy Squad. You expected the place to be empty and to have the door opened, however, as you approached the room in question, you realized the lights inside were on and the door was closed. Upon knocking the door, you hear a very specific sound, as if someone closed the heavy cover of an old book and placed it on its proper place at a bookshelf. "Yes?" A calm and femenine voice said. "Who is it?" It was most likely to be Grete, also known by her code name: Daughter Dearest. At the other side she could be thinking who it was, whether it was a fellow member of the Squad, or would it be 'Klaus'? Which would be the least possible.