When Sam has nightmares of their old home, the brothers return to Lawrence, Kansas to investigate. They discover that a new family has moved into the Winchester’s home, and the woman is the one that Sam has been dreaming about. The family has been hearing and seeing frightening things, and the brothers think it might be haunted by the thing that killed their mother. They enlist the help of their father’s psychic to rid the house of the angry poltergeist.
A woman is unpacking and going through old wedding photos when her daughter interrupts and says there’s something in her closet. The mother goes to check it out and finds nothing, then puts her daughter to bed while talking about how they’ll be happy in their new home. The daughter asks her mother to brace the closet door shut with a chair before she leaves. The mother goes downstairs to unpack and thinks she hears rats in the basement. Going downstairs, she finds the lights are out while upstairs, the chair moves itself away from the door as the daughter looks on in horror. The mother finds an old chest with photos of the Winchester family, while upstairs the closet door opens and a glowing flame emerges and the daughter screams.
In a hotel room Sam wakes up from a dream of a woman in the window of their old house, and he draws a sketch of the tree he saw there, and connects it to the one at their old house and thinks the family there is in danger. Sam reveals that sometimes his nightmares come true. Dean reveals he swore never to go back home but eventually agrees they need to go back there.
The brothers arrive at the house and they introduce themselves to the mother, Jenny, as…themselves for once. She recognizes their name from the pictures and lets them in, introducing them to her daughter Sarry and her son Richie. Jenny mentions there are rats in the basement and Sarry talks about the creature in her closet, and it was on fire. After they leave, Sam is determined to get her out of the house but Dean advises a more measured approach, and they check out the history of the house. They review their memories of the night their mother died but know very little now, then in the past. Dean steps away to go to the bathroom but calls their father and tells him on the voice mail that they’re at the old house and they need his help.
Jenny calls in a plumber for the backed up sink and when he’s working on it, a wind-up monkey starts up on its own. He tests the garbage disposal after making sure it’s powered off, but it starts up as the monkey claps on.
Dean meets with a garage owner, Guenther, who knew their dad and talks about how stubborn he was and hated to lose. Their dad claimed it was just a short circuit that caused the fire, then got obsessed with the supernatural and visited a palm reader. They check the phone book and find one psychic, Missouri Mosely, who is on the first page of their dad’s journal. They visit her and she recognizes them, and clearly has authentic psychic abilities. Missouri reveals that after the fire she introduced him to the supernatural and went to the house, but couldn’t pick up anything. Missouri reveals she’s been keeping an eye on the place and it’s been quiet, but wonders why now it’s active again. Sam wonders if something’s starting up.
At the house, Jenny is on the phone with the plumber’s lawyer when she hears noises upstairs and goes to investigate. At the house, Richie’s crib mysteriously opens up as does the sealed refrigerator where his juice is kept. Richie wanders over and crawls in for his juice when the door slams shut and locks him in. The mother returns and finds her son missing, and spots milk leaking out of the refrigerator. She opens it and finds him still alive but scared.
Sam and Dean show back up a few minutes later with Missouri and she talks her way in by getting Jenny to trust them. She senses a dark energy in Sam’s nursery but concludes it’s something different then what took their mother. Missouri looks in the closet as she senses two spirits, drawn to the “infection” left by the psychic wounds of the original monster. Now the house has a poltergeist that is determined to kill Jenny, although Missouri can’t identify the second spirit. She has some mystic powders that they can put in the walls and destroy the poltergeist. Missouri persuades Jenny and her kids to leave the house since she anticipates the spirits will get angry once they know what is happening.
As they prepare to place the powders, a lamp cord strangles Sam, knives hurl themselves at Dean, and a bureau rams into Missouri in the basement. Dean manages to rescue Sam by knocking a hole in the wall and placing the powder to drive the creature out of the house. They join up with Missouri and Sam wonders if they’ve succeeded. Jenny returns and finds the house in disarray, and the brothers clean up before leaving. Jenny goes to bed but wakes up later as her bed shakes wildly. Sam insists they stay outside in the car to watch, and he sees a panicking Jenny at the window just as he did in his dream.
The flame spirit appears in Sarry’s closet while Dean bursts in to get Jenny out and Sam grabs Richie. He comes into Sarry’s room and gets around the flame spirit to grab the daughter. He heads downstairs and tells Sarry to get her brother out before he’s grabbed by the poltergeist and pulled back inside, and the door slams shut with Dean outside.
Dean grabs a shotgun and an axe from the trunk and starts to break in while the poltergeist throws Sam around then holds him immobile while the flame spirit moves in. Sam realizes the flame spirit is…their mother, who appears in her natural form. She smiles and briefly acknowledges her sons, then apologizes as she commands the spirit to get out of the house before disappearing in a burst of flame.
Jenny gives Dean their photos while Missouri assures Sam all the spirits are gone. She explains their mother destroyed herself to eliminate the poltergeist. Sam acknowledges that he sensed something, but Missouri can’t explain what he’s going through. After they leave, Missouri goes back to her house…where John Winchester is waiting for her. John refuses to talk to his sons but says he can’t see them until he “knows the truth.”