My possible thriller idea

My thriller idea is about a small rural town in Alabama, where a string of suicides leads the town into confusion and disbalief about their town and the people in it. The film follows one teenager's death Harry Parker and his family life. The audience are unaware of why he died but focus more on the family. After the death the family are spooked by a strage presence in the house. This becomes the house's poltergiest. They experience paranormal activity in the house especially at night, like screams and cries of what seems to sound like Harry and furniture movement. Harry's sister Mellissa is worst affected by Harry's death and the paranrmal experiences and is eventually possed by his spirit. The family are tempted to contact an exorcist as has fits, screams Harry's name and even talks like him. However, the mother refuses as she is to depressed by what her family has gone through and does not want to believe in the paranormal.