Deep as the Eye Can See

In the small town of Dresden, Georgia, two people were found murdered along Interstate 20. One was a well-known and respected psychiatrist, Dr. Patricia Dean. The other was her husband, Dr. Robert Dean, a prominent cardiologist.
What made this murder so sinister was only parts of Robert Dean were found at the crime scene. The police have no fingerprints and no leads.
With the help of Patricia's sister, Crystal, and college friend Karen Andrews, a lead emerges that even state officials can't believe, which leaves the one question that everybody has been asking:
Where's the rest of Robert Dean's body?