Back of Beyond by C.J. Box

Cody Hoyt is a renigade police officer. Struggling with alcohol, he accidentally shoots the coroner. He's put on probation but that doesn't stop him from trying to solve a crime.

He hires an outfitter and together they embark on a trip through Yellowstone National Park to locate a horseback trip. Suddenly, they come across several victims and the hunt intensifies.

This is a well thought out thriller. Box keeps you guessing until the very end. It's a stand alone and I did miss Joe Pickett but it's definitely worth reading.

Ladybookbug!