Something is wrong—horribly wrong—in the deep woods of Oregon.
People age at accelerated rates and then disappear. Hundreds of disappearances have occurred in the area for decades—a veritable Bermuda Triangle on land. Even the authorities sent in to investigate the disappearances have gone missing. After that, the government stepped in and fenced off the entire area.
But when four strangers miss their train and wander onto the site searching for shelter, they discover what was left behind. After one of their four goes missing, they decide to leave the area. Something's toying with them, something ancient and malicious, and it doesn't want them to leave.
It's wise enough to understand them and powerful enough to control them.
It's also hungry, and it needs to be satiated.