Upstairs

You walk past one of the suit of armor statues guarding each stair case that winds up to the upper level of the mansion.  Directly ahead is the entryway to an expansive room theres a large bed that can be seen from the hallway light and other furniture.  You assume this is the master bedroom.

Down the hallway to the left and right are other doors a quick examination determines that there is an exercise room on the right and the left door is locked.

Away from the master bedroom and adjacent to the opening that overlooks the foyer are parallel walkways.  The one on the right leads to what looks like the mansion library.  On the left walkway is an entry to a guest bedroom.

You see that the main hallway extends in both directions so that a person could move from the exercise room to the guest bedroom as well as from the library and whatever is in that locked room.

enter Master Bedroom         enter Guest Bedroom        
enter Library         enter Exercise Room
try to open the locked door