Rent Twisted Nerve (1968)
3.6 of 5 from 71 ratings
1h 53min
It's taken me far to long to see this, it's availability isn't great and deserves a blu ray release really.
Ostensibly, Twisted Nerve is a dated, politically incorrect British thriller, but if you removed all of the dodgy language you'd actually have a rather liberal film which is trying in a rather ham handed way to show up prudish British values, archaic mental health research, racism and patriarchy.
That said, as a thriller it works well. Hywell Bennett is a nasty piece of work who plays the psychopath convincingly and with menace. His manipulation is calculated and cold and makes for some tense scenes.