Sam arrives dressed in a Victorian smoking jacket and holding a book and candle. He looks through the book and discovers it's Witchcraft in America
, dated 1879. Everything around him appears to date to that era. As Sam looks around the candle blows out on its own and he wonders how he could have traveled back beyond his own lifetime. He walks past a snake and goes up a staircase, and hears a moaning sound behind a door. As he opens the door, two monstrous figures leap out and Sam falls down the stairs, tumbling down to the floor below before being knocked unconscious.
The two figures reveal they're persons dressed up in monster costumes. The woman addresses Sam as Joshua Rey and checks to see if he's okay. The other person, a teenager named Stevie, apologizes for scaring Sam. Stevie has to go peel grapes and prepare gopher guts for the upcoming party. The woman, Joshua's fiancé Mary, assures Sam they'll be ready for the party. and says she can't wait until they're married. As he leaves, Stevie boasts that some day he'll write the scariest book in the world.
Once Stevie leaves in his old car, Mary figures that Sam is having a problem killing someone, and says he'll have to rewrite the entire book otherwise. She suggests he burn the character like Alice McHorner, the woman who lived in the house in 1692 and is supposed to haunt the place. They hear a banging noise upstairs and Mary tells the repairman, Tully, to keep things down. She asks Sam to go up and tell him to finish the windows by noon. Sam goes upstairs to Joshua's study and removes his costume for the haunted house, and finds Joshua's horror novels on the shelf and his current story in the typewriter. Tully looks in the window from where he's on a window and talks ominously of Sam writing horror novels and tempting evil. Sam notices there's a goat standing on the ground below. Tully talks about Alice and how she tempted evil and was burned at the stake. As Tully warns about the Devil, the goat pulls on the ladder and pulls it out. Tully falls to the ground below and breaks his neck.
Sheriff Ben Masters oversees the removal of the body and takes Sam's statement. When Sam mentions the goat, Masters observes that there's no goat present and Mary points out that they don't have a goat. Al appears and suggests it might be someone else's goat, but Masters notes that the next nearest farm is 20 miles away. As Mary goes inside to sit down and give Masters her statement, Sam suggests they should cancel the spook house. Masters admits that a lot of people will be disappointed and says that they have to carry on with their lives.
Once Masters and Mary leave, Al tells Sam they knew nothing about what happened. Sam wonders what he was there to do and Al explains that it's October 31, 1964, and Sam is a second-rate H.P. Lovecraft. At midnight, Mary is found strangled in the spook house. They go inside and Al explains that Joshua was the logical suspect, but there wasn't enough evidence to bring about his arrest. Sam figure she won't murder Mary now that he's in Joshua, so he's accomplished his mission and should leap out. He also wonders why Ziggy didn't pick up on Tully's death. Al points out that a nearby snake in a display case is a lethal black mamba.
Before he can continue, Mary comes from downstairs and wonders why Sam is talking to himself. As she goes past, she seems to sense something in Al's presence. The phone rings and Mary goes to get it, and Sam goes up to Joshua's office to talk in private. As they talk, a cat perches on the desk. Sam notices that Joshua's incomplete story now has new lines describing Tully's death, lines that weren't there before. Sam wonders if Masters is responsible, but Al suspects Mary. Mary calls up to tell Sam that Dorothy Yeager, the town gossip, is coming over with some candlesticks. Sam agrees to have her come over so they can tell Dorothy about Tully. Al says that he'll have the project run a diagnostic on Ziggy, and warns Sam to keep an eye on Mary.
Sam and Mary break the news to Dorothy, who admits that Tully was getting too old to do dangerous maintenance work. Mary goes to get Dorothy's candlesticks from the car and Sam brings up the subject of people that might have resented Mary ending up with Joshua. Dorothy admits that Masters wasn't happy when Mary chose Joshua. Mary returns and Dorothy goes to get some cider. Mary seems to react as Al quietly appears and informs Sam that Mary is definitely the one he's there for. Sam suggests to Mary they should cancel the spook house but Mary insists that Tully was an accident. They hear a scream from the kitchen and run out to find Dorothy dead. He notices a chewed matchstick nearby like the ones that Masters chews, and reaches for it. The black mamba slithers out, narrowly misses biting Sam, and slithers down a vent. Sam tells Al to do whatever checks he needs to, to find out who put the snake in the kitchen.
Sam and Mary go into town to report the death. Upon their return, Sam starts to go upstairs and notices the black mamba is missing. Al is there and insists that Mary is responsible. Sam doesn't believe it but Al suggests that she could have pushed the ladder from a lower window and put the snake next to the cider pitcher. Sam doesn't believe it and asks for a report on Masters. Ziggy hasn't turned up anything and the computer checks out perfectly. Outside, Mary hears Sam seemingly talking to himself. He goes to the typewriter and finds a description of Dorothy's death.
Meanwhile, Mary looks in and sees Sam talking to thin air, discussing Al's suspicions. She comes in and wonders who he's talking to, and Sam claims he's rehearsing dialogue for his book. Mary doesn't believe him but Sam notes strange and unexplainable things have been happening. Mary tells him to come right out and say he doesn't want to marry her. As she gets increasingly angry, a nearby skeleton vibrates and finally shoots off the wall and onto the floor, shattering. Sam accuses Mary of playing a trick and Al insists that Mary is a witch just like Alice. Mary suddenly goes into convulsions and Sam realizes that she's epileptic and need to get her to the hospital.
At the hospital, Al notes that Ziggy didn't report that Mary was an epileptic. Sam believes that epilepsy crosses the wires in the brain, and the short-circuited neurons may have stimulated her psychokinetic energy. Al is skeptical but Sam notes that Mary doesn't have a motive, so Al suggests they go to Mary's home and search for clues. They go there and find a lot of supernatural material. Al continues to insist that Mary is responsible and notes that despite the fact Mary is in the hospital, Sam hasn't leaped yet. Sam figures that means Mary is still the victim, but Al wonders if Mary's victim kills Mary in self-defense. Sam finds a list of the church deacons, and Mary, Tully, and Dorothy are all on the list.
Masters comes in and accuses Sam of being a schizophrenic horror novelist. Sam claims Mary sent him to get some of her things, but Masters says he came from the hospital and knows Mary hadn't recovered consciousness. Sam lies but it's clear Masters doesn't believe him. Sam notices a tattoo on Masters wrist, and Masters sarcastically claims he's the member of a cult and killed the others to cover his activities. However, he then says he was a Navy officer and got drunk one night and had part of an Air Force tattoo put on his arm. Masters accuses Sam of eliminating clues rather than hiding them, and Sam notes that he saw a match on the floor. Al goes to have Gushie runs some more tests and disappears, and Masters seems to sense Al's presence. he continues to insist he has nothing to hide as Sam leaves.
At the hospital, Sam brings flowers for Mary, who has recovered unconsciousness. She apologizes and Sam asks if there's anyone who might want to hurt her. Mary says there isn't and notices that Sam appears more confident. Sam promises to check on her later.
Sam drives back to the spook house and worries that time is running out, and Masters is coming. A truck pulls up behind him and bumps into him briefly, and then pulls off onto a side road. At the same time, the black cat from the house climbs over the seat. As Sam continues, a goat appears on the road ahead of him. Sam swerves to avoid it and almost hits Stevie, dressed as a scarecrow. The cat jumps on Sam and the car goes off the road and Stevie gets him out of the car. He explains that his own car broke down and was trying to flag Sam down. Sam explains he tried to avoid the goat, but the cat leaped in his face and the car suddenly developed a mind of its own, like in the novel Christine
. Stevie doesn't know what he's talking about, but says he didn't see a goat and Joshua doesn't have a cat.
Sam returns to Joshua's office and finds the Witchcraft
book open. As he reads through it, Al silently appears behind him and tells Sam that Ziggy still thinks he's there to save Mary. Sam believes Masters is responsible but Al points out that he couldn't have trained a snake and a goat. Al suggests that the boogieman might be responsible and points out that Sam's theory doesn't account for the goat. Sam calls the sheriff's office but discovers that Masters has disappeared in the last 30 minutes. Sam calls the hospital and discovers that Mary has checked out and is outside with the sheriff. Al tells Gushie to center him on the sheriff and disappears. Sam drives back and finds Masters' truck, crashed on the side of the road. Masters is inside, dead. Sam notices the goat in front of the truck but when he climbs out, it disappears.
Sam drives back to the spook house and finds the sheriff's truck parked outside, unharmed. Stevie is outside and tells Sam that Masters and Mary are inside. As Stevie tries to explain his idea for a new book, Sam abruptly tells him to go home. Sam goes inside and whispers for Mary. She comes out and says that Masters is in the kitchen. Masters comes out, unharmed, and says that it's about time. Sam confronts the sheriff and grabs his arm. There's a flare of red light, and Sam finds himself holding… Al.
Sam grabs Mary and heads for the door, but it closes and locks on its own. Sam confronts Al as he realizes that Mary wasn't in danger. Al says that she is now, and boasts that the others were a pattern, but it didn't add up. Sam realizes that it did: Al quoted a line of Tully when he wasn't present to hear it. He never walked through anything, or used the imaging chamber door. He disappeared without using the handlink. And most important, he was the only one present when Tully and Dorothy died. Al cackles and boasts of leaving the messages in the typewriter.
Al suddenly arrives, stepping in through the imaging chamber door. As he explains that he's late and something was screwing Ziggy up, he comes face-to-face with… himself. Sam explains that "Al" has locked them in, and plans to kill them along with the other three. Al checks and Ziggy can detect something, but can't confirm what. "Al" explains that he's the yin to the yang of God, and Sam realizes he's the Devil.
His enemy informs him he's there to put an end to Sam's meddling and grabs him by the throat. Al yells to Sam to fight back, since he can touch the Devil. Sam grabs the Devil by the throat as the clock strikes midnight and the piano plays by itself. Sam and the Devil begin to spin in place, faster and faster. The Devil takes on the face of his dead victims and books and shelves fly across the room. The Devil transforms into a goat and then finally Mary. There's a final burst of light…
And Sam finds himself back in the spook house, seconds after he fell down the stairs and recovered consciousness. Mary and Stevie have no idea what happened. Al appears and tells Sam they lost him for a couple of minutes. Sam confirms that Al is an untouchable hologram, and explains there were two Als. Al explains he's there to save Tully and Sam races upstairs and grabs the handyman just in time to keep him from falling. As he pulls Tully in, Al is surprised that Sam knew what to do before Al could say it. Stevie runs off to prepare for the spook house while Sam looks outside. However, there's no goat.
As Stevie leaves, Mary calls to his mother, Mrs. King, and Sam and Al wonder if it's the Stephen King they know. Sam wonders if he gave him all of his ideas, and he Leaps away