Photograph

Maya Hart and her best friend Riley Matthews are inseperatable. They made a promise; they can only be separated by death.
And they made the promise when they were just ten years old, so they didn't know much about death. But Riley suddenly gets the real meaning of it, full force. Too bad she can't tell Maya any of it.
Maya begins to self harm because Riley was her only friend. But then what happens when one day, Maya gets letters in the mail, telling her everything that she did in the day, saying that the person knows about her self harming, and knows about Riley's death?
But the scariest thing ever is what came with the letter: a photograph.