For old friends Roger (Peter Fonda) and Frank (Warren Oates) and their wives (Lara Parker of Dark Shadows and Loretta Swit of M*A*S*H), it was supposed to be "the best damn vacation they ever had." But their RV road trip takes a deadly detour at a secluded campsite when they accidentally witness a Satanic orgy and brutal human sacrifice. Now horror hits the highway as the couples are chased by blood-crazed cultists through some of the most intense crash-and-burn mayhem of the decade and into one of the greatest twist endings in drive-in history.