The door will lead to the cluttered room where you previously found the dev team photo. Manor Door #4 - Old Lumiere Travel to Old Lumiere and go to the Manor Gardens expedition flag.

The main goal of Blue Prince is to find room 46, and the key to this is opening up the Antechamber. Even if you reach Rank 9, and have a door connecting to the Antechamber, you won’t be able to ...

If you can’t access one of the red doors, try to place the Basement Key in a Coat Check room to keep it for later runs. To unlock the doors to the Antechamber, you’ll need to pull hidden levers .

Once you’re in the Garage, hit the garage door opener, right by the entrance. If the light on the switch is green, that indicates the garage door has power, and you’ll be able to open the door.