Extinction by Douglas Preston
Take an ingenious mystery and marry it to a near-future science fiction plot so plausible it feels more like a prediction than an invention and you'll have Extinction by Douglas Preston. Erebus Resort is nestled in the mountains of Colorado where scientists have de-extincted woolly mammoths and other large animals from the same era. They have been genetically modified to remove aggression (sounds foolproof) and left to roam. The resort is a top draw for the very wealthy. Newlyweds Mark and Olivia Gunnerson are two such park visitors. Until they disappear, leaving behind only a tent that has been slashed open and very large pools of blood. Frankie Cash of the Colorado Bureau of Investigation is called in. This is her first case as agent in charge and she sets about the investigation in an efficient and no-nonsense manner. She is also dealing with the uber-wealthy, an old-school sheriff complete with cowboy hat, and a large corporation that has untold millions at stake. Initially
