Pitch, scenario and treatment (EDITED)

Production Company: Lucrative Productions

Pitch: A rivalry between sisters leads to death.

Scenario: A couple madly in love Isabelle and Luke are the target of Isabelle's envious sister who wants Luke all to herself.

Treatment:
Isabelle and Luke are madly in love and have been together for 2 years, Luke thinks the times right and proposes to Isabelle. Isabelle is so ecstatic she rings up Elizah her sister to tell her the good news. Crisis strikes when Elizah is also in love with Luke. A jealous Elizah confesses her love for Luke to Isabelle and blackmails her to leave Luke or she will kill herself. Isabelle tells her not to be so ridiculous and go to bed and she will see her tommorow morning to sort this out. In a craze driven frenzy Elizah burns a photograph so the remains consist of just her and Luke. Rage driven and in a psychotic moment she takes her own life and only one person is to blame... The next morning Isabelle discovers Elizah dead and guilt takes over. Luke consoles her and reassures she's not to blame. But how VERY wrong he is!  From this day on Isabelle's life is not the same. Blood curdling creepy things start to take place which only Isabelle can witness such as doors slamming, candles flickering, Elizah's voice cursing in her ear every time she tries to get close to Luke, Elizah appearing and disappearing in a mirror whilst Isabelle is looking through it, dragging down the stairs, shadow of Elizah walking and Isabelle drowning in the bath. All these horrifying experiences take place with Elizah being present not physically but spiritually. Isabelle tells Luke who believes his girlfriend is just paranoid and still grieving. Elizah in a furious rage is sending all these messages from beyond the grave ruining Isabelle and Lukes relationship. She even tries to kill Luke by taking charge of his body and he attempts to strangle himself without willing to as she wants him to become a corpse like her, but Isabelle saves him. After this Luke finally believes Isabelle. The couple have had enough of Elizah playing games and trying to break them apart. Times up for Elizah when they discover a mantra for removing spirits and eventually Elizah leaves them alone.
 Locations and settings:
Woods, Grave yard, House.

I decided to change the version of my story again as i believe this is a more effective story line and fits the conventions of a horror film.