The film opens as Frank Stewart (Warren Oates), owner of a South-Western dirt-bike shop, is about to vacation with his best rider Roger (Peter Fonda) and their wives Alice (Loretta Swit) and Kelly (Lara Parker of Dark Shadows fame) in Frank's new luxury motor-home ("32 feet and gleamin'!"). After a long day's drive, Frank bristles at Roger's suggestion that they stop at an RV park. Frank argues that the reason they took their vacation in January was to "get away from the crowd", and says "we're self-contained, baby!". They turn onto an unmarked dirt road ("our private road to seclusion") and set up camp. Frank and Roger can't resist racing each other on the bikes they've brought along, and after crashing in a river, Frank delivers the deservedly-hated cliche that only Warren Oates could get away with: "I'm gettin' too old for this shit". Back at the RV, the couples have some wine over dinner,and Frank and Roger, already tipsy, continue the party outside. I envy those of you who cannot relate to the crappy folding-table scene that follows.
An explosion of flames across the way cuts the drunken conversation short. A group of robed people are dancing around a bonfire underneath a barren (and very spooky) tree while chanting in rhythm. Frank fetches his binoculars for a closer look. The leader makes a circle in the sand around them with a sword. After hoping that he'd see a hippy orgy, Frank sees the masked leader kill a girl. Before Frank can react, his wife comes out of the RV, telling him to get to bed. The Satanists hear this, and the "race" is on. The couples frantically make their escape in the RV, pursued by robed Satanists on foot.
The group arrives at a local police station, and meets with Sheriff Taylor (played by familiar character actor R.G. Armstrong, veteran of such horror flicks as The Car, Evilspeak, and Children of the Corn) who takes the men out to the site to look for evidence. They arrive at the tree, and a deputy takes a sample of what looks like blood in the dirt. The Sheriff's men spread out to search the area, and Frank finds the carcass of a dog on the tree.
In the meantime, Alice and Kelly are cleaning the motor home, and discover a note stuck to the edge of the rear window that had been smashed by the Satanists during their escape. The note contains a warning to be silent, and some occult symbols. Determined to decipher the threat, they boost some reference books from the local library. The note warns that any harm they inflict will be returned 9-fold. Frank and Roger wonder if the Sheriff is on the level. As insurance, Roger collected his own sample of the blood.
The group makes its way to an RV park, where ther women take a swim, but Kelly is convinced that she is being watched. The feeling returns that night in a redneck bar, where the steel guitar player in the band seems to have that Satanic look in his eyes. Returning to the lot, they find that "Ginger", Roger and Alice's lap dog, has been killed. None of the neighbors claim to know anything about the incident, so they drive off.
Trying to make coffee, Alice lets two large rattlesnakes loose in the cabin, causing Frank to crash the motor home. Eventually, Roger and Frank kill the snakes, but Kelly is at her wits end, and the men search the RV for any more Satanic surprises. They turn up nothing, but the fan has been damaged in the crash, and must be fixed before they can move on.
The next morning, Roger buries the dog as Frank completes the repairs on the RV. Preparing for all-out war, they buy a shotgun at the first shop they come across, and find that the telephone is suspiciously out of order. When the phone at the next stop is also out of order, they become even more alarmed.
On the way to the interstate, the debt the "Road Warrior" films owe to this movie becomes clear. A group of trucks tries to run the RV off the road, and Frank fights them off with the shotgun. Frank and Roger fight them off, and come to a roadblock. It seems a schoolbus has been in an accident. As they approach it, Frank says "I don't trust a schoolbus on a Sunday" and rolls right through. The RV is followed by several cars, and after they've been dispatched, the RV pulls off the road, seemingly out of danger.
Just as our survivors are about to pour martinis to celebrate their escape, they hear the tell-tale chanting outside. The Satanists are approaching, and Sheriff Taylor is among them. In an instant, the motor home is surrounded by a "circle" of fire, and the credits roll.
For Oates fans, the first 30 minutes or so are pure gold. For those who enjoy 70's satan movies, what this film lacks in quanity, it makes up for in the fine quality of the chanting and mumbo-jumbo.
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