A family trip to Ohio takes a terrifying turn when Jason, Valerie, Preston, and Shirley become trapped inside a flooded underwater tunnel after a sudden collapse.With no way out and their supplies running low, they search for another exit. But the deeper they go, the stranger things become. Whispers echo through the darkness. Shadows move where no one is standing. And then Preston disappears.When he finally returns, he looks the same—but something about him is terribly wrong.As the family struggles to understand what happened to him, one question becomes impossible to ignore:Did Preston find a way out of the tunnel… or did something find a way in?