The Other Hell (1981)
Italian nunsploitation/horror directed by Bruno Mattei (under one of his God-knows how many aliases, 'Stefan Oblowski'). Following the suspicious deaths of two nuns at a convent in (then) modern-day Italy, a priest attends to investigate the circumstances. Whilst there things he sees and hears lead him to suspect the supernatural may be at work, possibly even to the extent of demonic possession. As he sets about purifying the convent a third nun-death occurs in circumstances that leave him in no doubt that true evil is at work. He reports back to the bishop, who assigns a young hot-shot investigative priest (or 'ecclesiastical detective', as he refers to himself) to get to the bottom of things. However, the Mother Superior resents the young priest's presence and is openly hostile, hindering his efforts to the point where the priest begins to suspect she may be involved in some way. As the priest's investigation delves deeper he begins to experience increasingly bizarre phenomena and realises that his own life is in danger.
Bruno Mattei isn't exactly regarded as one of the greats of Italian cinema, but damn if I didn't find this a lot of fun. Mattei was renowned for 'borrowing' from other directors' work if he thought he could make a quick buck from it, and this film has elements of The Exorcist, The Omen, Suspiria, Rosemary's Baby, and Carrie, but he strings them together pretty well. Yes, it's batcrap crazy, and wildly inconsistent (great makeup effects as one character's stigmata begin to bleed, terrible makeup effects on another character's burnt face), but it's really atmospheric and has a terrific finale. Bizarrely, there's no nudity or sex(!) but it still gets a 7.5/10