Fires came from two seeds. When I was eighteen, I saw a newspaper article about a forest fire that had come down from the hills and was eating through a suburb, and the image of fire fighters fleeing through a landscape of inflatable pools and playground slides stuck with me. Also, I read Kate Millett's The Basement, which is about the Sylvia Likens murder. It is one of the most disturbing stories you'll ever hear. In retrospect, I'm sure that is where the image of a kid locked in a basement came from.
I think of this now because it was just pointed out to me that someone has made a movie based on the Likens murder. It is called An American Crime. Here is the trailer. I know I will see it eventually. But I recoil--I had trouble watching the whole preview.