How do I get to the detached room on the first floor?

Hint 1 of 3:

You can only get to this room when you've done every other puzzle that's
available to you.  The detached room will be the next to last room in the
game (the attic is last).

Hint 2 of 3:

Look closely around the first floor for new supernatural events.  Clicking
on one of them will take you to this detached room.

Hint 3 of 3:

To be specific, look in the foyer for that new event.