the film open with the on screen paragraph this film be base on actual event that take place in a central european country not many year ago . yeah and course it be . during the credit we see a yet unknown nun in confession . then we be introduce to sister gertrude ( anita ekberg ) who work in a hospital with a dr. poirett ( massimo serato ) and her roommate and friend sister mathieu ( paola morra ) and other people work there obviously but these be the only one you need concern yourself with at this point . sister gertrude have recently undergo surgery to remove a brain tumour and have be experience headache and black out and a loss of control . dr. poirett say that he think she be suffer from post operative shock and the symptom that she describe be purely psychosomatic . in actual fact sister gertrude have become addict to morphine . sister gertrude receive no support from her mother suerior ( alida valli ) a she tell sister gertrude that it a nun vocation to suffer . after dr. poirett refuse to prescribe her anymore morphine and sister gertrude steal a ring from a dead patient and pawn it in the city buy the drug with the proceeds . sister mathieu steal morphine for her as well from the hospital . the patient and dr. poirett begin to notice that sister gertrude personality have begin to change and for the bad . one night sister gertrude notice that a patient name josephine ( nerina montagnani ) have put her false teeth into her glass of water on the dining room table during dinner . angry sister gertrude throw them on the floor and stamp on them . later that night josephine have a heart attack in her room and dy and this be when sister gertrude steal the ring . soon after this incident sister gertrude sens dr. poirett be become suspicious and talk to the director ( daniele dublino ) of the hospital and convince him to fire dr. poirett . thing become bad for sister gertrude a father janot be bludgeon to death and throw out of a high window to make it look like suicide . more deaths occur a the new doctor and patrick roland ( joe dallesandro ) can not quite believe what be happen at the hospital and he too also start to have his suspicion about sister gertrude . be sister gertrude a drug addict killer . since the hospital doesn not want a scandal they try and cover up the death a accident but eventually the truth be reveal . co write and direct by giulio berruti i really do not think too much of this european exploitation film . the script by berruti and alberto tarallo be quite slow at time and surprisingly shy away from the strong sleaze and exploitation element you may expect from a euro film from this period and of this type . a bit of nudity and a sequence where a female patient give a man in a wheelchair a blow job and have sex with him and a scene where a woman have needle stuck into her face be about it . the film be set almost entirely in the hospital and the fact that ekberg play a nun be totally irrelevant and not really use to it full potential . there be not enough suspect on show either and i always felt that it be go to be one of only two potential killer and i be prove right . and the film title killer nun tell you just about everything you need to know as well . the killer motif be never really make that clear and the way they be reveal at the end be one of the poor and most unimaginative i have ever see and the killer unmasking be well in an average murder and she write ( 1984 1996 ) episode . i just do not care about anyone or anything in this film and and that never a good thing . quite well make on a certain level but there be so many more well film out there in this genre . dull and unexciting and somewhat uninteresting . not worth spending good money on that for sure .