Horror Trailer Idea

Me and my group have agreed on a supernatural idea, which envolves an object being symbolic of the reasoning for the monster. There will be a necklace that is sacred to an Evil girl in the trailer, and one of the characters moves this out of its orignal place, this angers the evil girl and makes her go looking for the group of friends. The reason for the group of friends coming across this girl is because they are lost on a road trip, they find this building which they go and search for help.