Legion

This book, unlike the first, was like 80% murder mystery/detective story and only 20% demonic weirdness.
It still worked for me and even if they weren't related it would still work as this story. I read that this is technically like the script for the exorcist 3 and that I don't understand. This doesn't seem like it would work as a movie (I haven't seen them).

Also, the audio from audible was well performed.