Sarah Jane receives a puzzle box from a Verron soothsayer, with the instruction to give it to the person she trusts the most. She gives the puzzle box to
Maria. A meteor is on a collision course with Earth, and Sarah Jane has set up, but not yet activated via Mr Smith, a force field to deflect the meteor. The next morning, Maria wakes to find that Sarah Jane and
Luke have gone missing, but no one besides Maria knows who Sarah Jane or Luke are. A woman called
Andrea Yates has apparently taken Sarah Jane's place. Andrea was present when Sarah Jane fell off a pier to her death at age 13. When Maria goes to Andrea to talk to her about this, but when Andrea gets reminded of it, she fully panics and angrily evicts Maria from "her" house and Maria says that she will do anything necessary to bring Sarah Jane back, Andrea rushes to her attic, where she takes out a second puzzle box. She remembers making a deal with a hooded figure called
The Trickster. When Sarah Jane and Andrea were 13, Andrea made a deal with the Trickster to switch places with Sarah Jane when she lost her footing and was about to fall off the pier; she had forgotten the Trickster until the present. Unknown to Andrea, the Trickster removed Sarah Jane from Earth's timeline so the meteor will destroy it and create the chaos on which he feeds. In the present, Andrea accepts the Trickster's deal to make Maria disappear. The Trickster dispatches a
Graske, who captures Maria just after her father,
Alan, picks up the first puzzle box. Subsequently, no one besides Alan can remember Maria. Remembering Maria's suspicions, Alan questions Andrea at her birthday party, who takes him to the attic and reveals the truth. Alan is chased into the street by the Graske but he knocks him down, then uses his device to bring back Maria, though Sarah Jane is still not back. They return to the attic, where Sarah Jane appears in the mirror and explains to Andrea that witnessing her death caused tremendous pain for her and gave her the resolve to fight pointless deaths herself. Andrea revokes her deal with the Trickster, causing her to fall off the pier to her death when she was 13. Sarah Jane and Luke reappear in the attic in the present and activate Mr Smith to divert the falling meteor. Alan demands an explanation of Maria's involvement with aliens and supercomputers.
Continuity • The
Graske also featured in the interactive episode of
Doctor Who, "
Attack of the Graske". Sarah Jane states that there was Graske activity on Earth a couple of years ago, possibly referring to that episode. • Sarah mentions previous times she saved the Earth and thwarted alien invasions, including the Bane ("
Invasion of the Bane"), the
Slitheen (
Revenge of the Slitheen) and the Gorgons (
Eye of the Gorgon). She also mentions that she helped defeat the Patriarchs of the Tin Vagabond. The Church of the Tin Vagabond was previously mentioned in the 2006
Doctor Who episode, "
The Satan Pit". •
The Trickster threatens the
Doctor when in limbo. This is the second time that the Doctor has been explicitly named in the series, the first being in
Revenge of the Slitheen. The Trickster makes good on this threat in the
Doctor Who episode "
Turn Left", when a creature from "[his] brigade" assaults
Donna Noble. • Sarah Jane's address is identified as 13 Bannerman Road, as it is throughout the later series; it had been 21 Bannerman Road in the preceding two serials, yet the sign on the brick wall next to the Smiths' driveway still says 21. ==Outside references==