Horror Trailer Idea

The idea my group and i have come up with bases the story around a supernatural necklace and a young female ghost with sentimental connections to it. We will aim to make the genre a crossover between a psychological horror, and a supernatural horror. The necklace is within a room where the girl protects it from harm due to the sentimental feelings she has for it. The main protagonist is a female (final girl) who gets lost during a road trip and stumbles across the room. Her and her 2 friends (1 male/1 female) find the room whilst searching for residents who could possibly point them in the right direction. They inadvertently find the necklace and take it with the ideological view of 'finders keepers'. After leaving the room the trio split up and the girl seeks to take back the necklace, by any means neccessary.