I just finished watching this British horror film on Netflix. It's a devastating ride into madness and horror, as a abused wife, played by Yvonne Mitchell, hatches a scheme to murder her abusive husband, played to the hilt by British horror maven, Michael Gough, who is also sadistic toward his 16-year-old daughter, Jane, here played by Sharon Gurney.
There are some twists and turns, especially the dénouement that will leave you speechless.
I highly recommend it.