Alison Parker, a beautiful but severely neurotic fashion model (Raines) moves into a gorgeous Brooklyn brownstone house that has been divided into apartments. The house is inhabited on the top floor by Father Halloran (John Carradine), a reclusive blind priest who spends all of his time sitting at his open window. Alison begins having strange physical problems, including insomnia, and has some terrifying flashbacks of her attempted suicide. She complains to the real estate agent of the noise caused by her strange neighbors, only to be told that the house is occupied only by the priest and herself. The behavior of her "non-existent" neighbors becomes increasingly surreal and disturbing. It turns out that the building is owned by a secret society of excommunicated Catholic priests, and is a gateway to Hell. The blind priest is the guardian who ensures that the demons do not escape. The priest is nearing the end of his life, and a new guardian is needed. The society has chosen Alison because her two suicide attempts qualify her as the perfect candidate. She is told that she must pay for her sins by becoming the next Sentinel, and only by doing so she will be allowed into Heaven.
In the climax of the film, Alison is confronted by her neighbor Charles Chazen and all of the minions of Hell. Among them is her boyfriend, Michael, who was secretly killed earlier and is damned for killing his wife. Alison is chased through the building by grotesque and deformed creatures. She runs to the top floor and into Father Halloran's room where the demons corner her. Chazen hands her a knife and convinces her to commit suicide to avoid this torment. Father Halloran and another priest, Monsignor Franchino, enter the room. Franchino supports the infirm Halloran as he wields a large crucifix. They work their way through the hordes of demons and reach Alison, where they prevent her suicide. She takes the crucifix from Monsignor Franchino, and sits down in Father Halloran's chair. Shortly after, the brownstone is demolished and replaced with a new, more modern apartment complex. Mrs. Logan, the realtor, attempts to persuade a young couple to move into one of the apartments. The couple asks about the neighbors, and Mrs. Logan explains to them that there are only two: a violin player and an old, blind nun. The nun is Alison, now blinded like Father Halloran, who sits at the open window in the top floor apartment. From Wikipedia
MICHAEL WINNER (1977)