SPOILER ALERT: the following article contains massive spoilers, including the ending. If you have not yet seen the movie, proceed at your own risk, or better, come back to this article later!
SPOILERS AHEAD
The Devil Below Plot Summary and Synopsis
There is an abandoned place nestled deep in Appalachian country where underground coal mines have been ablaze for decades. When a team of researchers try to find out how the fires started, they soon discover something more startling than the mystery that sent them there: they’re not alone.
Source: Wikipedia (CC BY-SA 3.0).