Don't Look in the Basement (1973)
Director: SF Brownrigg
Starring: Bill McGhee, Jessie Lee Fulton, Robert Dracup
Plot: Nurse Charlotte Beale arrives at the isolated Stephens Sanitarium to work, only to learn that Dr. Stephens was murdered by one of the patients and his successor, Dr. Geraldine Masters, is not very eager to take on new staff. Charlotte finds her job maddeningly hard as the patients torment and harass her at every turn, and she soon learns why Dr. Masters is so eager to keep outsiders out.
I picked up this movie as part of a 12-movie DVD set called American Horror Stories, which I bought while visiting the US a couple of years ago. Most of the movies are public domain stuff (House on Haunted Hill, Bucket of Blood, Little Shop of Horrors) or very bad prints of other 60s and 70s horror. While the picture quality of this 70s indie cheapie (apparently it cost $100,000 and was shot in 12 days) isn't great, luckily the movie itself makes up for that in spades.
Also known as The Forgotten, this was the debut for late director SF Brownrigg, who does a great job of building up a tense atmosphere. The acting, all by unknowns, is rough around the edges as you'd expect, but does a great job of conveying the various mental short-comings of the inmates. There are some genuinely chilling moments and a bit of blood is shed here and there.
The setting and opening kill (axe to the head while chopping wood) invoked comparisons with Friday the 13th: The New Blood, while the rest of it kind of reminded me of a low-budget Shutter Island. I won't go too much into the plot since there's a pretty good twist involved (which veteran horror movie fans will probably guess but is good anyway).
I highly recommend Don't Look in the Basement, although fans of more modern and polished horror might not find it to their liking.
As a post-script, I should mention that the director's son has helmed a sequel, the trailer for which you can find online. I'm looking forward to checking that out when it's released.