One Step Too Far: A Novel (Frankie Elkin Series, Book 2) by Lisa Gardner 
 
From #1 New York Times bestselling author Lisa Gardner, a thrilling new novel that sends missing persons expert Frankie Elkin into a national forest in Wyoming looking for a young man who disappeared without a trace.  But when the search team encounters immediate threats to their survival, Frankie realizes she’s up against something very dark—and she’s running out of time.