My plot: Revenge

The film starts with three teenage, college student friends who are having a movie night at one of the friends house while the parents are out on the town. They are happy, having a laugh and looking forward to a good night in. However, things are not all that they seem..
Just as the friends begin to watch their film, the power suddenly blacks out, will not switch back on and they are forced to sit with nothing but a few torches from the kitchen drawers as a light source. As the night draws on, the friends become bored from not watching the film and decide to just explore the house and the area around the house as a way of entertainment, but they are not alone. Outside, waiting in the darkness, is a mysterious hooded figure watching them, looking for the opportunity to take their revenge on the three friends over a past event that the unsuspecting teenagers thought was long buried and over...
The friends notice something is not right once they explore the house and keep hearing faint bumps and creaks around the house. When they return downstairs, they find that the back door is open, that someone has either entered the house or had entered the house. Too scared to run down the eerie street to any of the neighbours, the friends lock the back door  and try to call for help from their mobiles, but nobody can get any signal. The friend who lives in the house runs outside, deciding that she is not going to sit around scared and intends to go and get help from a neighbour. However, before she can get away from the house, she comes face to face with the hooded figure.
She runs back inside before the hooded figure can strike, locking the door behind her and breaking down sobbing. Her friends come to her aid and once she stops sobbing yells "Its him!" and "I thought he was dead or something, he disappeared over a year ago!"
The girls friends look outside but see nobody and try to calm their friend down. As she calms down, she goes over to the picture of her brother, who has been missing for over a year and claims he was the boy outside in the hood. The three friends become worried, as they used to bully the girl's brother to death because of all the attention he got compared to his sister and he was getting bullied at school anyway, which changed his behaviour slightly. He eventually snapped and killed their cousin who was staying the night, but he meant to kill his sister instead, as the cousin was sleeping in his sister's room. After he had murdered his cousin, the boy went missing.
The friends try to run upstairs, hoping to get signal on their phones, but as they get half way up the stairs, they hear a smash. They return to the living room to find that the picture of the girl's brother smashed out of the frame and besides it a single picture of the girl's cousin who the brother killed with the words "it should've been you" written on the back of the picture.
Throughout the film, the girls are stalked by the boy and they become increasingly paranoid that he is out there, waiting for them. People refuse to believe them and the boys who bullied the kid are stalked and murdered one by one.
To protect her friends, the girl decided to face her brother, which ends with a massive stand off and her killing her brother in self defence.