The Floyd County Jailbreak, by Michael Giles

Some secrets survive wars. Others survive the people who created them. October 1929: When five prisoners escape from the Floyd County Jail, Sheriff Mike Norman believes he is facing nothing more than a dangerous manhunt through the Blue Ridge Mountains. But one quiet prisoner—engineer Elias Mercer—is the real target of the escape, and his disappearance draws the sheriff into a mystery that began during the final days of the First World War. Following a trail of forgotten government installations, abandoned quarries, hidden chambers, and long-buried records, Mike uncovers a conspiracy that powerful men have spent eleven years trying to erase. Every clue leads deeper into the mountains—and closer to a secret known only as Project Sentinel. Perfect for readers who enjoy historical mysteries, small-town sheriffs, Appalachian history, and carefully crafted whodunits where every clue matters.