At the same time, a local councillor (and authority on transport matters who's critical of the "smelly liberal anti-road brigade") has been murdered (seemingly at the hands of local smelly liberals), so they're off investigating who did that when another couple of deaths occur.
Sure enough the killer's caught, but along the way we have discussions of religion vs. atheism, and Christianity vs. Paganism (because of the belief systems of the victims). All of that's interesting, and somewhat thought provoking, it's just it's a little dull. there's too much talk, and not much action.
My other complaint would be Jane (Watkins' daughter). In the first few books she was your typical spunky teenager. Now she's coming across as moody.