A family's mountain vacation near Reno, Nevada interrupted by the arrival of a disheveled man hauling a trailer behind an ancient Cadillac. Pop, as he calls himself, tells the family a tall tale about the son he lost to illness. The family feels sorry for him and befriends him . . . not knowing the danger that is soon to come to them. In reality, his son Bernie is crazy, deranged and dangerous and kept straight-jacketed and chained up in Pop's trailer. Pop lets Bernie out only to stalk and harm campers while Pop helps himself to their belongings.