Hi, im trying to find out the name of a film i seen years ago, the plot is, 2 young american couples are taking a trip across country in a camper van , one dark night the stop to rest, and come across a group of satanists making a human sacrifice, they witness the sacrifice and are discovered by the satanists and are forced to flee, but this is not the escape as everyone they then come across turns out to be connected with the satanists and they are continually fighting for their lives, even the authorities are not to be trusted, i forget the ending or maybe i never caught it as i was very young at the time, as i said i believe it was from the 70's, maybe the early 80's
thanks