Savannah Cole is most at home where the light can’t reach, deep inside Mammoth Cave. As a guide and geological researcher, she’s mapped its treacherous veins for years, using limestone and silence to shield the old wound that never healed: her father, once a respected journalist, vanished while investigating corruption in their small Kentucky town. Since then, Savannah has trusted no one and spoken even less.

On a routine tour through a rarely used passage, she spots something that doesn’t belong in stone, a piece of surveillance equipment. Before she can examine it, a blast tears through the tunnel and the ceiling comes down. This isn’t a natural collapse. Someone set a charge…and meant to bury the truth with her. Savannah claws her way to the surface and straight into Graham Lancaster, former best friend, now a sheriff’s deputy and heir to the town’s most powerful family. He’s the last person she wants help from and the only one who believes the fear she can’t hide.

Refusing to run, Savannah cracks open her father’s old files, cryptic notes, clipped articles, half-finished reports about land fraud, missing people, and rumors of secret tunnels beneath town. The dots connect to one name: Graham’s estranged brother, a ruthless developer whose projects touch every permit, donation, and closed-door meeting in the county. Graham moves Savannah into protective custody. Safety lasts hours. A sniper’s shot shatters his window; a “safe” hunting cabin turns into a midnight ambush; they flee through the backwoods, wading a freezing creek while dogs and men with night vision sweep the trees. Injured, exhausted, and out of options, they realize the cave system that once hid Savannah may be their only way to survive.

Hidden Ridge is a high-stakes romantic suspense set in America’s longest cave system, where every echo could be a footstep and every shadow a threat.