It sounds like there's a lot going on in this book. First, the general world situation with the deadly fog gives it a post-apocalyptic feel. Add a murder to that, and you've got a very dramatic situation! As a twist to the typical murder mystery, nobody (even the killer) remembers what actually happened, and if they don't solve it quick, they'll all succumb to the fog. (Because of course, the victim was one of the few people responsible for the system keeping the fog at bay.) I'd love to read this, it sounds fascinating and exciting!