A group of people are trapped on an island and haunted by an evil witch.
A pregnant woman runs away from a group of men carrying farm implements. She comes to a large abandoned building 50 miles from Boston, and her crystal necklace shines in the light. She enters the building and is followed by the men and then jumps to her death out a window. A pregnant Jane Brooks wakes up from a nightmare and then stares at herself in the mirror. Leslie walks through the same building the woman ran to and stares out of the broken window the woman jumped out of. She is surprised by Gary, who gives her a cup of coffee and tells her he thinks she has been working too hard. She then reads from a book on Witch's Light written by a German author. Jane buys a toy for her brother, and as she is walking home, she is almost crushed by a falling I-beam, but is saved when the Lady in Black shines her crystal into her face, causing Jane to stop just short of being crushed. Tommy Brooks is playing with a ball when the Lady in Black picks it up and hands it back to him. The Lady in Black then tells him that Jane bought a present for him. Leslie thanks Gary for coming with her to take photographs for her book and when he starts talking about their relationship, she quickly changes the subject. Gary brings up how Leslie is still a virgin and she asks him to drop the subject.
Jane asks Rose Brooks why she wants to buy a building, which is the same one the woman committed suicide from, and Rose tells her it is the perfect place to turn into a club. Freddie Brooks tells her the architect cancelled and she finds a new one, Linda Sullivan. The Lady in Black appears to Linda and when Jon answers the ringing phone, Linda takes it from him. Linda then agrees to meet with the Brooks. Leslie continues to read from her book on Witch's Light and Gary tries once more to have sex with her, but she tells him to go to his sleeping bag. The Lady in Black gently rocks a baby crib while speaking in German. While searching the building, Leslie sees a reflection of the Lady in Black in the glass of the broken window the woman jumped from. Tony Giordano tells the Brooks that Jerry Giordano will be the one taking them to the island with the building. On the wall of the office is an enlarged and framed print of a Boardwalk property card from the Monopoly game. While sitting in the real estate office, Freddie stares intently at the Secretary, who catches him staring at her. While walking along the pier, Tommy is greeted by Cindy. After Tommy tells her his dad plans on buying the island with the building, Cindy tells him her mom told her a witch lives there. While staring out of the broken window, Leslie and Gary see light reflecting from the Witch's Light and Gary takes a photo of it. Linda arrives at the real estate office and she, Rose, Jane, Freddie, Tommy and Jerry take a fishing boat, owned by Fisherman, to the island.
Freddie asks Jerry why it was hard to find someone to take them to the island, and Jerry tells him there are legends about the island. Jane shows Tommy how to use his new toy which allows someone to record and play back a message. Leslie sees the fishing boat on its way to the island and her and Gary hide. Fisherman tells Jerry if they aren't back by low tide then he is leaving them, and the group heads towards the building. Tommy wanders around the building and runs into the Lady in Black, who tells him no one lives in the building. As the Fisherman is drinking from his bottle, he sees a reflection of the Lady in Black and a bright light shines in his face. The fishing boat slowly moves on its own away from the island as the Fisherman hangs dead from its nets. As Jane is grabbing for a medicine bottle she dropped in a half filled tub, she is pulled into hell. As she wanders around she comes across Demons fighting over a baby fetus. She wakes up with everyone surrounding her, and Jerry suggests they get back to the boat. They arrive at the pier and find the fishing boat gone and decide to go back into the building. Tommy sees the Lady in Black and points her out to everyone. They walk into the house and find Gary walking down the stairs and he tells them why he is there. Gary suggests they use his rubber dinghy to get off the island, but Jerry thinks the water is too choppy. Rose demands one of Jane's pills and after Jane can't find them, Tommy offers to look for them. The Lady in Black hands him the bottle of pills and he gives them to Rose and tells her the Lady in Black gave them to him.
Rose finds a wall safe and as she looks inside of it, she is pulled into hell. Leslie tells Jane that the book she is translating tells of a pregnant witch that sacrificed herself rather than being burned to death for witchcraft. All of a sudden the projector starts playing and plays an image of the Lady in Black and of the woman being chased and jumping out of the window. The Lady in Black says that there are three doors to hell, the first one leads to greed, which is represented by Rose, who has her lips sewn shut by Demons. Tommy puts his toy outside of the Lady in Black's room and records her chanting. Linda remarks that she is cold and Freddie suggests they start a fire in the fireplace, where Rose has been put upside down by the Demons. Rose slowly burns to death as her skin peels away. Gary again tries to have sex with Leslie, but she stops him. While Jane is looking for Tommy she goes inside of the Lady in Black's room and sees the empty baby crib and touches it. Linda and Jerry start to have sex, while Freddie spies on them. Tony goes to the Sheriff and tells him Jerry hasn't come back yet. The Lady in Black says the second door to hell is the door to lust, and Linda and Jerry are transported to hell. Linda and Jerry get separated and Jerry sees Linda choked to death. Tony goes to a bar and tries to convince a fisherman to take him to the island with the building, but the fisherman refuses to take him. Jerry is nailed to a cross by the Demons. Freddie takes Gary to the room Linda and Jerry disappeared from and they find Linda impaled on the tip of a sail fish. The Lady in Black mentions the blood of the virgin and as Leslie is sleeping in bed, she is transported to hell and raped by Satan. She wakes up back in the room and discovers she is no longer a virgin. Gary, Jane, Tommy and Freddie go looking for Jerry and find him crucified upside down and in flames.
Leslie tells the survivors that everything that is happening is part of an ancient ritual. They then discover Rose's body in the chimney. Gary retrieves a flare gun from his dinghy and fires it into the air. Cindy sees the flare and tells her dad and he doesn't believe her. She then calls the police, but no one answers. Leslie translates the words on Tommy's toy, which mention greed, lust, fruit of a pregnant woman and blood of a virgin and realizes they are all elements of witchcraft. The Lady in Black covers an effigy doll in the handkerchief Freddie dropped and stabs the effigy doll. Freddie starts to bleed from his nose and his veins start to bulge. His veins eventually erupt from his hands and neck and he dies. As he does, Jane starts to go into labor. They hear a helicopter, which Tony and the Sheriff are using, but as they try to leave, all of the doors shut. As Tony and the Sheriff are about to fly off, Gary grabs a flashlights and starts flashing it, which Tony briefly sees, but they fly off when the Sheriff thinks it is nothing. After the helicopter leaves, they realize the doors once more can be opened. Tommy points out the Lady in Black to Gary and Leslie and they go towards where he pointed.
Leslie notices the window is no longer broken and they enter the Lady in Black's room. The Lady in Black turns around and instead of the Lady in Black, it is a possessed Jane. The Lady in Black, using Jane's body, tells them that their souls are being used to feed her existence. She then tells them the last door to hell is anger. Gary and Leslie run to escape the building and run to the rubber dinghy. Gary goes back to get Tommy and finds him in a room with his toy. As he walks towards Tommy, Gary is stabbed through the chest by a metal candle holder. Leslie runs back into the building and is stalked by Jane. Tommy runs up to Jane and she starts to choke him. A dying Gary crawls into the hallway and yells. Tommy drops his toy and it starts to play his recording telling Jane he loves her and she jumps out of the window to her death. Leslie is brought to Greenbrier Hospital and is told by the Doctor that Tommy is okay and so is Leslie's baby.