Don't Forget to Scream

Don't Forget to Scream is a short story centering around a character called Amy and her possible paranoia. Amy firmly believes that something, not someone, is following her - possibly trying to kill her.
She confides in Doctor Munson - a so-called therapist - who puts Amy's feelings down to her having an over-active imagination.
Towards the end of the story, we are left with the question: Was Amy truly being followed or was it simply her imagination/paranoia? Is she alive or dead?