From the liner notes

Girls on the Road follows two young teenagers on their first road trip who meet up with a hitchhiking Vietnam Vet (Michael Ontkean) and head to a hippie retreat by the beach. Unfortunately, all their laid back groovin' out and free lovin' ways are interrupted by a serial killer targeting young girls.

Two wild teenage girls, Debbie (Kathleen Cody) and Karen (Dianne Hull, Fifth Floor, Aloha Bobby and Rose) hit the road for some freedom, boys, and unexpected danger in this 1973 drive-in classic! The girls pick up a handsome Vietnam veteran (<Michael Ontkean, "Twin Peaks", Slap Shot, Maid to Order) who is still troubled from his time at war, but is trying his best to fit in. They all end up at a hippie encounter session run by John (Ralph Waite, "The Waltons", The Bodyguard) in a peaceful village by the ocean. It's all fun and games until the girls discover that a serial killer is murdering girls.