I wasn’t aware South Africa produced horror movies until now, which is something new for me. This was one of just three films director Austin created throughout his career (1968-99)—all released in the early 70s—as he primarily worked in television; and honestly, considering its production quality, it felt like a TV movie. The story centers on a vineyard/plantation with enslaved people who practice witchcraft, and the owner is hiding something: a brilliant twin brother who was initially dismissed by the medical field, but after suffering a severe brain injury a year prior, he’s essentially lost his mind and kept locked away in the mansion's attic. It was reasonably well-made and perfectly fine for late-night viewing. It really could have been improved if someone more skilled had worked on it. The core concepts were quite intriguing, even though they weren’t explored as effectively as they could have been, and I found the ending to be entirely foreseeable, but still enjoyable. I got a copy of this film very inexpensively as part of Mill Creek's 'Nightmare Worlds' 50-movie collection, and it's something you can watch without expecting anything extraordinary.

Source on TMDB