Treasure State by C.J. Box

Private detective Cassie Dewell is hired by Candyce Fly to find the man that conned her out of millions of dollars. The previous detective on the case went missing in the small town of Anaconda, Montana, so Cassie figures that's a good place to start her investigation. The other case that Cassie is working on involves trying to uncover the identity of the person who hid "Sir Scott's Treasure," a treasure that has people from all over trying to find it. Cassie has actually been hired by the treasure originator because he is wondering how easy it would be for someone to discover who he is. This person figures that if it's hard to find his identity, then it will be equally as hard to find the loot. Since that is what he wants, he is hoping Cassie doesn't succeed. Treasure State is the latest novel in the Cassie Dewell series. It will be published in September.