Writers resource (some spoilers)

At the heart of the story is Farasset house. Built in 1901 by a brilliant physicist turned devil worshipping occultist. He designed an array capable of altering reality. He died before activating it and it sat dormant attracting ghosts for over a century.

The house was acquired by the protagonist's brother's (Keith) company which repaired it for a haunted house attraction. Opening night they inadvertently activate the array, giving the horror exhibits life.

The first two floors are defined, the third an attic are left for any monster a writer can imagine (goblins, mind flayers, Britney Spears, the list is endless).

The only rules (and they can be bent if the story is good enough) are that exhibits can't leave the house (or stray far from their exhibit). Anyone corrupted by an exhibit may leave the exhibit and even the house.

Three VIP tickets are in the hands of potential protagonists, but with some writing it can be as little as one (arg my friends bailed) or even four or five.