Thriller Idea(s)

my initial idea:
A note is seen on the bedside of a table as she wakes up. She looks closer and concentrates on the note, she sees a blood stain on the note.
Late on in the day, the girl is out with her friends, in the background there are a bunch of people playing football. The ball rolls over to the girl, she then picks it up to throw it back to them. On the ball, there is the same note as she saw before. She then looks back to her friends and sees them all injured with all cuts and bruises over them. After seeing her friends injured, she looks down to her own arms and there are cuts appearing.
On the note, the words "you have been warned" are written. It is signed off as "!X!x!".
The reason this may not work is
It would be hard to picture what might happen next. The conventions would be more of a horror than a thriller.







New idea.
Picture of friends in bruises and cuts around room
girl locked in room
bruises/cuts seen on her lower arm
she is seen rocking back and fourth/seen walking around room, walking up to pictures, running her finger over faces.
thought track by person from the outside - possibly a therapist???
notes posted around her room
at the end, seen writing "save me from the dark" on the wall
The reason this may not work is because 
There will be too many questions rising such as why this girl has pictures of this incident and who this girl is. Although questions are good, there may be too many question which will cause too much confusion.