As a late-going patron of the drive-in thearers (1970's-1980s), there are many movies that I have seen & forgotten. This is one I could never forget. Despite its low-budget, exploitation-style of movie-making, the STORY was very well done. The isolated therapy-asylum, where patients act out their fantasies in order to help cure their phsycosis, the accidental murder of the head doctor just as the new nurse arrives on the scene, the (supposed) assistant doctor taking over, the various crazy paitents, the revelation that the assistant doctor is actually a patient herself, and, finally, the rescue of the young nurse by the simple-minded Sam, who killed everyone else in the house so she could escape unharmed, made for a great STORY, which held the film together. I emphasised the word STORY because that's what makes a good or great film. No matter how much blood, gore, nudity, sexual matter, or outrageous behaviour you put in a film, if the STORY is not good, then the film is not good. The film credits show clips of all the actors, including the old hag with the final line telling you to get out & never come back, which is a great ending to this film. If it is out on video/DVD, see it & enjoy it.