A conflict develops between a troubled Vietnam veteran and the sister he lives with when she becomes involved romantically with the army buddy who reminds him of the tragic battle they both survived.

Frank and Roger and their wives take off for Colorado in a recreational vehicle, looking forward to some skiing and dirt biking. While camping en route, they witness a Satanic ritual sacrifice, but the local sheriff finds no evidence to support their claims and urges them to continue on their vacation. On the way, however, they find themselves repeatedly attacked by cult members, and they take measures to defend themselves.