I imagined that dark passage listening to one of my favorite Pat Metheny tunes. Are You Going With Me? Over and over again. The images in the video below don't match the landscape in the book but they do justice to the tune. You have to listen to the end to truly scale the Grapevine. I think you'll understand when you get there.
You can read the Grapevine section of book at the RAW FICTION website. It's an AUDIO EXCERPT, meaning you're supposed to listen to this very same tune as you read, like a sound track. It's a different version, featuriing the haunting voice of Anna Marie Jopek, a Polish singer.