The story opens with a "mad woman" in the attic, in the year 2059 in Ealing, where Sarah Jane and Luke are long gone and Mr Smith is no longer functional. A teenage boy, Adam, investigates the attic, and learns that the "mad woman" is Rani Chandra, who had fought aliens with Sarah Jane, Luke and Clyde. Rani has a flashback of 2009 in her childhood, aged 15, in Sarah Jane's attic, at which time she overreacted when the group were not paying her much attention. Sarah Jane told her that a flash of lightning that struck the BT Tower was unimportant. Rani then received an email from an old friend, Sam, from her home town by the beach, whom she had told about her encounters with aliens.
The e-mail explained that people had been disappearing; Rani meets up with Sam, who sends her to investigate rumors of a demon in an abandoned funfair. Rani then meets Harry, the caretaker, who she accompanies after lying to him about having a twisted ankle. Harry becomes frightened and tells Rani to leave, but she then sees people with red glowing eyes seemingly enjoying the funfair rides.
Sarah Jane, Luke and Clyde investigate Sam, who has lived at St Anthony's Children's Home since his parents died in a car crash in 2001. Leaving Luke with Sam, Sarah Jane and Clyde go to the funfair where they discover the red-eyed people on the rides. Rani is shut in a room with Eve, a girl with red skin, who "just wants to play" and reveals that she is kidnapping lonely people to make them have fun. Rani is then convinced that she does not need to depend on Sarah Jane and that she should leave her forever. She then glimpses her future... as the mad woman in the attic.
Rani sees her future as a mad woman and wants to change it. She leads Eve out of the 'haunted mine' ride. Eve takes control of the rides again, but Harry tells her to stop, as it will kill her, according to Ship. Eve then possesses Rani, like the other people in the fairgroung.
Harry, Clyde and Sarah Jane then take Eve back to the beach, and K-9 gives Ship the black hole energy it needs to leave, also allowing K-9 to return home permanently. Rani is let free. Sam and Harry are invited to leave Earth with Eve.
As Sarah Jane and her friends are about to leave, Ship grants Rani's wish that Sarah Jane, Luke and Clyde would leave her alone, not understanding that it was not intended literally, and they disappear.
Adam reveals that he is the child of Sam and Eve, and he gives the older Rani the opportunity to change her past. Rani's timeline is altered so that Ship does not fulfil her wish. She is then shown in her alternative future, enjoying the company of her children and grandchildren.