It's true--it really is #1 on the worst movie list at IMDB, and by a big margin. It's also indexed as movie [0060666]...coincidence?
The plot, such as it is, concerns a family which becomes lost on a road trip in Texas, and find themselves staying the night at the home of the Master, who is 'not dead as you know it.' The house is looked after by the caretaker, Torgo, the movie's one redeeming feature. He has a hideous thigh disfigurement (apparently, he was supposed to be a satyr), and a manner of speaking that seems designed to be satirized. The 'haunting Torgo theme' that accompanies him on the soundtrack will drive you nuts for days afterwards.
Needless to say, the best (and, hopefully, only) way to see this movie is the MST3K version, one of the funniest two hours I have ever spent.