Plot
A group of seven senior students (Jackie, Elizabeth, Kate, Karen, Susan, Adelle, and Rosemary) at the all-girls Catholic Trinity College are sent to spend four days cataloging a large art collection in the now-empty Welles mansion, the contents of which have been bestowed to the college. The mansion has had a longstanding reputation for being haunted by a vengeful female ghost.
The elderly Sister Urban oversees the project, and is surprised upon arrival to be met by Dr. Robert Fisher, who presents himself as a prospective buyer of the home. On the first day in the house, Jackie finds a diary dating back to the 1930s of Jennifer Welles, a Trinity College alumnus and the niece of Tyler Welles, the home's original owner. In the diary, Jennifer makes reference to Sister Urban, and writes of her longing to become a nun herself. When Jackie brings up the name to Sister Urban during dinner, she recounts to the young women how the orphaned Jennifer was killed at the mansion in an accident.
That night, all of the girls, aside from Jackie and Adelle, propose that they hold a seance in an attempt to contact Jennifer's spirit, which ends in apparent poltergeist activity. After everyone else has gone to sleep, Jackie and Elizabeth find a large portrait of Jennifer in the parlor, which bears a striking resemblance to Jackie. Unable to sleep, Jackie continues reading Jennifer's diary, and learns that, while staying in the mansion, Jennifer was subject to sexual advances from her uncle Tyler, and that the two eventually engaged in an incestuous relationship.
The next day, an unnerved Jackie and Elizabeth attempt to conceal the portrait from the others while cataloging items in the house. Sister Urban begins feeling ill, and spends the remainder of the night bedridden. Meanwhile, Rosemary is murdered with a meat cleaver by an unseen assailant while riding in a dumbwaiter. The others assume Rosemary is playing a prank when she fails to meet them for dinner. Karen goes searching for her in the basement, and finds her body stuffed in the dumbwaiter before she too is killed. Kate is subsequently murdered outside when she is dragged into a pond by a rotting, decomposed hand.
Shortly after, Jackie's boyfriend, Paul, and his friend, Bruce, arrive at the mansion, startling Susan. While Paul locates Jackie, Bruce is run over and killed by Paul's car outside. Meanwhile, Sister Urban becomes progressively ill, and Elizabeth and Susan, who have been standing vigil at her bedside, grow worried. Susan is lured into the attic, where she is locked inside and electrocuted to death, causing her body to become incinerated. Jackie and Paul begin searching for Adelle and Bruce. While searching outside, Paul is stabbed to death with a pitchfork by the killer, posed as a sculpture donning a babydoll mask.
Jackie, unable to locate anyone, stumbles upon Sister Urban in the hallway, and finds her in a confused, feverish state. After putting Sister Urban back to bed, Jackie goes into the basement, where she finds all of her classmates' corpses (save Elizabeth, who has been kidnapped and is still alive) seated in chairs before a ceremonial altar. She is met by Dr. Robert Fisher, who is in fact Tyler Welles, seeking to marry Jackie as he believes her to be a reincarnation of his dead niece. Meanwhile, Sister Urban manages to summon Jennifer's spirit, which possesses Jackie, allowing her to enact revenge on her Satanic uncle Tyler, killing him by gouging out his eyeballs, avenging her murder by him decades prior. Jackie, Elizabeth, and Sister Urban manage to flee the house in an ambulance. As they drive away, an apparition of Jennifer looks down from an upstairs window.
