The Caverns of Stillwater is a mystery involving a private investigator named Bernd Devlin (Berns). Berns inherits a large estate from John Lincoln, his unknown uncle, in Stillwater, Missouri. To collect the inheritance, Berns must go to Stillwater, a small town in rural southern Missouri.
Once Berns gets to the small town he is thrown into a serial killer mystery. He discovers that John jealously guarded the caves surrounding his homesteaded estate. Those same caves seem to be the killing grounds of a serial killer stalking the rural countryside.
The local Sheriff believes that John was the killer. Others believe John was set up. In order to protect the inheritance, Berns must discover who the serial killer really is, before he ends up the next victim.
Berns spends some time getting to know John through his friends and enemies. He gets some powerful insight into John from the town's only clergy, Pastor Mike. Berns' gut instinct tells him that John was not the killer. In fact, Berns thinks that John was murdered by the serial killer as a cover up. So does Dean, one of John's friends. While delving into John's life and death, Berns' own life is at risk. He is the victim of vandalism and run off the road in the middle of the night.
Berns, still determined to collect the inheritance, investigates John's house where he finds bullet fragments. Berns begins to doubt John's innocence, but decides to hold off judgment until more facts are discovered.
Berns meets Jessie, a local who was John's close friend. She helps him throughout his investigation. They begin a dating relationship while puzzling over John's death and investigating the serial killer. Berns realizes this mystery is much more than protecting his inheritance, but, instead, is about clearing the good name of his uncle.
They discover John's investigation files, but have little time to review them before Berns becomes the intended victim of arson. Berns decides he should head back to Miami to review John's files. But, while waiting at the airport, he is served with a wrongful death lawsuit. He decides to head back to Stillwater to finish what he started.
By the time he gets back to Stillwater, much has changed. An ex-girlfriend appears, trying to prospect for Bern's fortune. The local Sheriff is missing. And Jessie's best friend, Dean, is missing.
