In an apartment complex, an old woman takes the lift. In one of the apartments, Claire tells her son George to get to bed but he complains about the noise from the lift. She says that he needs to put the things he doesn’t like in the cupboard, and George insists that she do the special thing. Claire turns the lights on and off five times and then puts him to bed. As he goes, George quietly pleads for someone to save him from the monsters. As Claire tells her husband Alex that their son is in bed and needs a doctor, George turns on his torch and shines it around his room, begging for someone to save him.
In the TARDIS, the Doctor receives a sudden shock and checks his psychic paper. The message, “Please save me from the monsters” has appeared on it. As he programs coordinates into the TARDIS, he tells Amy and Rory that he’s making a house call. They land and go into the building.
George cowers in his bed and listens to something making moaning noises. Meanwhile, the old woman passes outside in the hallway, pulling her cart.
The Doctor explains that a scared child sent him the message and somehow it got to them in the TARDIS.
Alex is looking at photos of his wife and son while watching the TV. In the next room, George continues to look around his room. Meanwhile, the Doctor, Amy, and Rory knock on doors and try to find the child. Rory talks to the landlord, Purcell, while the Doctor talks to the elderly Mrs. Rossiter. None of them have any luck.
George finally gets out of bed and goes to the window. Amy and Rory go by as he watches, and the Doctor sees him. He checks briefly with his companions and then goes to George’s apartment. As they take the elevator down, it suddenly plummets out of control to the ground floor. When the doors open, Amy and Rory are gone.
The Doctor knocks on Alex’s door and the husband assumes that it’s the doctor that Claire as going to find. He invites the Doctor inside.
Mrs. Rossiter takes her trash to the bins and starts to go back inside. Something stirs among the bags and Mrs. Rossiter calls upon the person to come out. She assumes that it’s George and approaches the bags, and something pulls her in.
Alex explains that George has been a strange child ever since he was born, and is now 8. The Doctor confirms that George has gotten worse recently and has become scared of everything, and promises to do his best.
Amy and Rory wake up and find themselves in a dark room. Rory figures that they’re dead but Amy tells him to shut up. They start exploring, unaware that a shadowy figure is behind them.
George continues to look around his room. When it appears that the bathrobe hanging on the door, he jerks with fright and knocks over his lamp. Alex comes running in and George insists that he wasn’t asleep. The Doctor comes in and says that he’s there to talk to George about the monsters.
Amy and Rory enter a deserted kitchen and find a copper pan that is actually wood painted to look like copper. In one drawer they find a large glass eyeball, and Rory’s pocket torch starts to flicker. Amy grabs the fake pan and an electrical torch from a counter and they continue exploring.
The Doctor chats with George and then offers to put his toys in the cupboard. George reacts with fright and Alex explains that they put anything that scares George into the cupboard. The Doctor carefully approaches the cupboard and starts to open it, but someone pounds on the front door.
Rory and Amy explore the endless corridors of the house while the same shadowy figure follows them.
Purcell is at the door and comes in with his dog Bernard. He tells Alex that it’s time for the rent. While Alex tries to explain that he’s out of work, the Doctor uses his sonic screwdriver to scan the room. When George expresses an interest in it, the Doctor uses it to activate the boy’s electronic toys. He then scans the cupboard and is horrified to discover that the readings are off the scale. While he approaches it, George overhears Purcell subtly threatening his father. Once the landlord leaves, Alex goes to his son’s room and starts to open the cupboard door. The Doctor stops him and explains that George’s monsters are real.
Amy and Rory finally find the front hall and an outside door, but it’s locked and there’s no knob. Amy finds a grandfather clock with the hands painted on. A child’s laughter echoes through the room and they hear footsteps running away.
The Doctor makes tea while Alex complains that he’s just playing into George’s fantasies. When Alex tells him to leave, the Doctor refuses and explains everything he’s seen and how something has amplified George’s thoughts so that he could receive them.
Mrs. Rossiter walks through the endless halls of the shadow house, calling for help. A figure with the laugh of a small child stalks her. Meanwhile, Rory and Amy try to find the source of the child’s laughter and realize there’s more than one child. The companions finally find a door and Rory opens it. Inside is what appears to be the dummy of a child with a grotesquely large porcelain head. They go back the way they came, unaware that the “dummy” behind them has come to life.
The Doctor looks over Alex’s photos of his family and realizes that something is wrong, but can’t figure out what. He considers opening the cupboard but Alex reminds him that he said it was dangerous. The Doctor then decides not to open the cupboard, but then goes to open it.
Purcell is trying to watch TV. When he gets up, his foot sinks into the carpet. In a matter of seconds, Purcell is pulled into the floor and disappears as Bernard looks on.
The Doctor, Alex, and George go to the cupboard and the Doctor opens the door. There’s nothing unusual inside. However, the Doctor realizes what is wrong with the photos. He brings them back and Alex what he remembers about the day that George was born. Alex finally realizes that Claire was unable to have children, and the Doctor points out that in the photos taken right before George was born, Claire isn’t pregnant. Both men look at George and the Doctor asks who he is. The toys start to shake and the cupboard door shoots open. The Doctor and Alex are pulled back into the cupboard as George chants to be saved from the monsters. They are finally pulled inside and the doors slam shut.
Amy and Rory are still exploring when Purcell runs up to them. One of the doll figures grabs him and transforms him into one of them. The couple run off and lock themselves in a room as the doll figures walk after them and say they want to play. When they can’t get in, the doll figures go away.
The Doctor and Alex find themselves in the dining room of the same house. The Time Lord quickly realizes that they’re inside of the dollhouse inside of the cupboard. Alex demands to know what’s going on and the Doctor explains that there is a perception filter functioning, a filter powerful enough to change everyone’s memories. As they walk through the house, they pass one of the doll figures.
The doll figures try to break down the door until Rory manages to barricade it.
The Doctor tries to work out what’s going on but is interrupted when they hear the sound of the lift. The five electrical candles flicker and then go out.
George hears the lift from his bedroom and grows frightened.
Amy tells Rory that they have to take control and let the doll figures in, and then fight their way out. He reluctantly agrees and they open the door. Rory gets past them but the doll figure grabs Amy and transforms her into a doll as her husband stares in horror.
Alex realizes that the five candles correspond to when they had to turn the lights off and on five times when they put scary things in the cupboard. The Doctor explains that the cupboard has become a repository for all his psychic fears. A doll figure comes in and the Doctor tries to hold it off with the sonic screwdriver, but it doesn’t have any effect. The Doctor grabs a giant pair of scissors and drives the doll back long enough to escape.
George approaches his cupboard.
As Alex tries to hold off the Amy doll and the others as they close in, the Doctor realizes that George is a Tenza, one of a race of alien beings that drift through space, find families in need, and assimilate into their household. More of the dolls close in as the Doctor explains that George doesn’t consciously realize what he’s doing. He calls out to George, telling him that he has to believe that he’s safe. Meanwhile, the dolls cut him and Alex off on the stairs, while more dolls drive Rory down the stairs from above.
George reaches for cupboard door and finally opens it. Inside the dollhouse, the dolls go inert and George appears in the hallway. The Doctor tells him that he did it, but the dolls come back to life and renew their assault, advancing on George as well. Thinking back, the Doctor realize that George overhead Alex and Claire talking about sending him away. Alex admits that his son isn’t human, but when he hears George cry for help, he runs down the stairs to him, knocking away the dolls and hugging him. He promises George that he will never send him away.
Everyone is restored to normal with only a vague memory of what happened. Claire returns home from work and finds Alex, George, and the Doctor playing in the kitchen. The Doctor informs Claire that George is now fine. As he goes, the Doctor assures Alex that George should be fine now and will adapt perfectly now. The Doctor leaves with Rory and Amy, haunted by the memory of his coming death.