The Playing Fields First Draft

The last thing Claire Fischer remembered before waking up in a strange field was her walking home from a party. The field has a supernatural air to it, a feeling enhanced by the clothing she finds in a strange trunk, and a note explaining the rules of the "game".
Five humans.
One monster.
The humans need to find three key components to open a gate that leads to their freedom.
Sounds simple enough, except the note didn't tell them what kind of monster would be stalking them, nor did it rule out the possibility of a changeling. Claire and her fellow abductees must unmask the monster, avoid it, and find the three components for their freedom.