A young couple from the city, Mike and Sheryl, sets out for a camping tour in the West Virginia countryside. While making love in the woods they are discovered by three young local guys with rifles and a jar of self-made alcohol, which they force-sell to them. They seem to be the bad guys but as we will see, they're not. They also meet a middle-aged, rather conservatively dressed woman with a little wooden cart on a forest trail, who sends them on the Timber Falls trail, claiming that would be the most rewarding of all. She also asks them if they are married, which they are not (remember this for later). Next person they meet is a park ranger, who reassures them of the beauty of the Timber Falls trail. This happens shortly after Sheryl forces Mike to get rid of their handgun. He throws the bullets in a little creek.They arrive at a beautiful lake where they set up their tent and make love in the night. Somebody is watching them from outside the tent.The next morning Sheryl takes a swim in the lake and is abducted by a strange looking figure. Mike awakes and can only find Sheryl's necklace in the water.After meeting two of the three guys again and having a fight with them suspecting them of taking Sheryl, Mike gets caught in a bear trap and passes out.He awakes in a farmhouse and is taken care of by the woman they met earlier, called Ida. He gets suspicious after a while and asks her to call park service, which she declines. Soon the real scheme becomes clear: It is all a trap set up by Ida and the park ranger Clyde, who are in fact a couple who live there, desperately trying to get a child, but all their attempts so far have failed because the fetuses die in the womb. They want a (married!) couple so the husband can get his wife pregnant in their basement dungeon and, after nine months, they hopefully have their baby (the young couple would instantly get killed afterwards, of course). All their dead fetuses (10 or 12!) are on display in the dungeon in large jars with name plates attached.Now we get fully introduced to the strange beauty of the dungeon underneath the farmhouse: a crazy and distorted catholic shrine with a big crucified Jesus with a blinking X-mas light chain around him and many candles. Sheryl is strapped to a gynecologist's chair and while trying to rescue her, Mike gets caught and is chained to the ceiling of an adjacent torture chamber by a grotesquely disfigured man (he took Sheryl from the lake), later identified as Ida's brother Deacon, who got severely burned in the face in an "accident" years ago, constantly exposing his teeth. He doesn't talk since his vocal chords were also destroyed. His favorite weapon is a double blade sickle.After a surreal "wedding" with Clyde serving as a priest ("The child must be conceived in wedlock", they state, being totally deranged fundamentalist catholics), Mike and Sheryl are then left alone to have sex and Mike is supposed to get her pregnant, which he refuses. Mike is then tortured by Deacon with a whip and alcohol. Later, as he still refuses, cussing and calling them sick perverts, he gets burned with a red-hot branding iron but still refuses. Sheryl gets her pinky finger hacked off because since he refuses, she's the one to get tortured. Sheryl also reveals she's already two months pregnant, making the "wedding" useless since the child was conceived "in sin".The other park rangers get alerted when a report comes in regarding the missing couple. The three young locals also get suspicious and try to rescue Mike and Sheryl but all die violent and gory deaths.In the end Ida gets decapitated, Clyde gets his throat cut with a scalpel, Deacon gets burned alive and Mike and Sheryl have lived through their ordeal.One year later, back home, they put their cute baby to sleep, Mike still walking with a cane, when the camera pans to the window....and we see Deacon's double blade sickle emerge outside. END CREDITS.
Output: Question: What to Mike and Sheryl do when left alone?, Answer: Have sex