My Pitch for a Horror Movie

My original idea for a horror movie was to feature a group of college friends going on a night out. The night would go a complete success with everyone having the time of their lives. as the night draws to a close, the last methods of cheap transport stops and the nightlife begins to die down, the friends all try to find a place to stay. They stumble across a very old building and in their drunken states, decide to go and take a look. After establishing that there was not a soul on the grounds, they all agree that it would be the perfect place to stay. As they settle in, they begin to hear noises and start to see shadows of things lurking in the dark and one by one, the friends get killed leaving the final girl. The final girl becomes so emotionally unstable that she kills anything that may be inside the grounds, eventually being killed by the supernatural being that had taken her friends lives.