This is book 7 of the "Joe Pickett" series.

This note contains spoilers for the book.

 

Pickett, having gotten fired from his job as a game warden, is re-hired and put to work as the new governor's trouble-shooter.

There's plenty of trouble. A lawyer has encountered a party of National Park workers from Minnesota in the portion of Yellostone in Idaho—where the laws don't apply. (Well...there is at least a colorable argument that a jury cannot be empaneled that meets the constitutional requirements, and hence that a trial cannot be held. It's called the "Zone of Death", and it's real, though there do not appear to have been any stories as drastic as this one in real life.)

What's going on is insanely big, involving an extremophile bacterium living in the Yellowstone hot water pools which converts coal into natural gas, and which some people want to release into a huge underground coal field to harvest the gas (coal being rather out of style, and gas harvesting being less disruptive to the overburden).

There's also concern about the Yellostone super-volcano being 40,000 years overdue for destroying most of North America. Spoiler: That doesn't happen, in this book.