Working on a mystery story

I am formulating a horror mystery story in my mind. Now I have to get the outline on paper. I like horror that forces the character to face their fears, biases, and preconceived notions. I also want to have the characters have a positive change in their lives. I believe that horror can alter the course of a person's life in a positive way. Is there anyone that has felt the same way? Love to hear your ideas and stores.