Not quite a mystery, more like an adventure
Headlock is an entertaining story featuring author/private investigator Jeff Reynolds. His paranoid client wants him to find out whether his (the client's) father was murdered.
The plot gets a little complicated from there, and there is a sidebar of wrestling, but it's not difficult to keep the characters straight. There are many subplots that come together to form the whole.
I've never been to Walla Walla, but I have been to Mukilteo.