The highest room in the Mansion belongs to @The False Queen, the creator and controller of the mansion. Although she is an automaton, there is no information available to hint at who created her. She keeps the party in the mansion by controlling the physical plane around the mansion. The only way to escape is to do enough tasks in and around the mansion to befriend the false queen, or find a way to cut her off from her control, or destroy her. If the party destroys the false queen that will turn all current NPCs in the Mansion hostile towards the party, making their saftey when leaving the mansion less than assured.
If the party survives lond enough to become friends with @The False Queen she will drop the barrier and allow you to come and go from the Mansion at will, winning the game.