After you find out everything you can about Mary, including her last name and what she did while she was still alive --
How do I find out more about Mary?
-- send Joey up to talk to her again. This time, choose the topic "The review."
Mary gets upset and goes down to the lobby, looking for the other people she thought were in the building. Follow her.
If you've played any of the other Blackwell games, you know the procedure. Have Joey offer her his tie, and she's home safe.
If only you could say the same about the guy outside ...
What just happened to that man?!