Probably the best horror movie of the period in the late 60s and early 70s when low-budget filmmaking was at its peak. A nasty, harrowing, film, free of gore but full of violence, both visual and aural (indeed, this film has an amazing soundscape, something which often goes neglected in the visual medium). Scooby Doo as seen through the heat haze of a brutally hot Texas summer, four hippies and their dog (in this case, Franklin) being terrorized by men in masks. Only this time, they aren't insurance scammers, but much much worse.