Chris (DESMOND HARRINGTON) is driving through rural West Virginia on his way to Raleigh when he runs into a traffic jam that won't be cleared for hours. Not wanting to be late for his interview, he decides to turn around and try to find a way around the gridlock. When his cell phone won't work, he stops at a rundown gas station to call about being late, but the phone won't work and the one-toothed attendant isn't of any help.
Chris then spots a map and decides to take a detour on Bear Mountain Road, unsure of whether it's finished or will even get him where he wants to go. Along the way, however, he's distracted on the winding forest road and ends up crashing into a vehicle stopped dead in the middle of it.
Its occupants -- Jessie (ELIZA DUSHKU), her friend Scott (JEREMY SISTO) and his fiancée Carly (EMMANUELLE CHRIQUI) and their friends Evan (KEVIN ZEGERS) and his girlfriend Francine (LINDY BOOTH) - aren't hurt, but also made an impromptu stop due to a string of barbwire that seemingly was in place to blow out their tires.
With two of them staying behind to watch the vehicles, the other four head off for help. Along the way, they find a rundown, backwoods mountain house. No one's home, so they decide to go in for a bathroom break and to use the phone to call for help. Inside, they find what look like human organs inside many jars and then have to hide when the three disfigured and apparently inbred owners return - with one of their dead and very bloody friends.
From that point on, the four spend the rest of the day, night and following day trying to elude the homicidal mountain men who are intent on catching and killing all of them.