When seventeen-year-old senator's son Grant Tavish is involved in a fatal accident, all he wants to do is face the consequences of what he's done. But those consequences never come, even if headlines of "affluenza" do. The truth soon becomes clear: due to his father's connections, Grant is going to get away with murder.
As a family tradition approaches, a cave excursion on the Appalachian Trail, Grant seizes the opportunity to take justice into his own hands by staging an accident and never coming back. But before he has a chance to enact his plans, the cave system collapses, trapping him miles beneath the surface with four other teens from much less fortunate circumstances. As they struggle to survive, they share their innermost secrets and fears, and just when it seems they might be on track to finding a way out, they realize...
There's something else down there.
And it's hunting them.