"The day I was born, I saved the world. Now I've helped to destroy it."
— Luke Smith
Luke and Maria start their first day at their new school, but not everything is as it seems, the cafeteria food is mouldy, the air smells like batteries, people are spontaneously getting ill and worst of all, the portly head teacher has gas problems. Aided by their new friend, Clyde Langer, Sarah Jane and the gang discover a sinister revenge plot engineered by the Slitheen, for what the Doctor did to another branch of their family.
Tropes
- Abusive Parents: Jeffrey Slitheen puts his son down in favour of Luke… in front of him.
- Adventure Rebuff: Both Sarah Jane and Maria try to make Clyde go away for his own good. It doesn't work.
- Age Lift: Janine was supposed to be in her twenties in the script, but it seems the production was unable to find an overweight actress in that range, as in the broadcast version she is considerably older. The novelisation uses her originally intended age.
- Avenging the Villain: The Slitheen are partly motivated by the loss of their family members on Earth in "World War Three".
- Bland-Name Product: Clyde's Wolverine brand body spray, a play on the real brand "Lynx".
- Blunt "Yes":Sarah: Are you threatening me?Janine: Yes.
- Chekhov's Gun: Clyde brings in a cold chip sandwich to eat at school as an alternative to the canteen food after it goes rotten, eliciting a terrified reaction from Jeffrey Slitheen, who hurriedly disposes of it in the fish tank. When Clyde recounts this to Sarah Jane when the power cuts out, this helped them figure out that vinegar kills the Slitheen.
- Continuity Nod: Slitheen in Downing Street, which happened in "Aliens of London" and "World War Three", and Sarah Jane learned about from Rose in "School Reunion".Sarah Jane: (remembering) Slitheen in Downing Street.Maria: What?Sarah Jane: Something a friend said once.
- Kist Magg Thek Lutiven-Day Slitheen said that Glune Fex Fize Sharlaveer-Slam Slitheen had bought the plans for the machine from a Wallarian.
- Glune mentions Clom, twin planet of Raxacoricofallapatorius and homeworld of the Abzorbaloff from "Love & Monsters". He also mentions the Judoon and the Blathereen family, who appeared in the novel "The Monsters Inside", as enemies of the Slitheen.
- Mr Smith has data on Abaddon.
- Culture Equals Costume: Several of the Slitheen who are summoned to the school are dressed this way to indicate the global scale of their plan.
- Death of a Child: Implied but not shown; Korst, the young Slitheen, is disguised as one of the students at Maria and Luke's school. Given what is revealed about Slitheen disguises in their first Doctor Who appearance (and the real Mr Jeffrey is seen meeting a similar fate at the beginning of the story), the real boy must have been killed and skinned, but this is not directly stated.
- Dramatic Irony: The audience already knows that the Slitheen are weak to vinegar, but it takes Clyde and Sarah Jane a bit of Awesomeness by Analysis to deduce it.
- Even Evil Has Loved Ones: The Slitheen beg Sarah Jane and the others to let the young Slitheen live.
- Evil Teacher: The Slitheen pose as teachers worldwide during their revenge plot.
- Exposed Extraterrestrials: Slitheen, when not in human suits.
- Family-Unfriendly Death: Downplayed, but Mr. Jeffrey's death is unusually nasty for the show, and carries with it the clear implication that the real Carl, a boy the same age as Luke, Maria and Clyde, met a similar end.
- Fat Bastard: The Slitheen, as usual.
- Foreshadowing: The scene at the end when Clyde asks Mr. Smith where he came from and the computer responds by shocking him foreshadows a revelation in the season finale.
- The Glasses Come Off: A rather dark version; when Blakeman is standing the real Jeffrey against the wall of the secret room so the Slitheen can Kill and Replace him, he pulls off Jeffrey's glasses as the Slitheen about to assume his identity won't need them.
- Gory Discretion Shot: Mr Jeffrey getting his head stoved in by a Slitheen might not be appropriate for a childrens' show airing at 5 pm, so it cuts to Blakeman's reaction just before the claw makes contact.
- Hold Your Hippogriffs: "Oh, for the love of Clom!"
- Impersonation-Exclusive Character: Mr. Blakeman, the headmaster of Park Vale before Rani's father takes over the following year (Blakeman is mentioned as having "mysteriously disappeared" in the interim), as he's already been replaced by a Slitheen some time before the story starts.
- Incest Subtext: Between Glune, the headmaster Slitheen, and Kist, the science teacher Slitheen, which might help explain why the Slitheen are so screwed up.
- Kill and Replace: All of the Slitheens' human disguises, although Jeffrey is the only one seen meeting this fate onscreen. (The novelisation adds a prologue where the real Janine is killed.)
- Killed Offscreen: The real Blakeman and Janine were both killed prior to the events of the story; it is not clear if the "real" Carl is present in the canteen or at the science club, or if he has already been killed and replaced at this point.
- Large Ham: All of the Slitheen.
- Lost in Transmission: As the Slitheen begin to drain London of power, Mr. Smith informs our heroes that the Slitheen are "notoriously hypersensitive to *fzzt*", and they're left to figure out the end of the sentence from the information they already have.
- Nice Job Breaking It, Hero: Luke gives the Slitheen the equations they need in response to a transparent ploy that you'd have to have been born yesterday not to see through. Unfortunately for Luke, he Really Was Born Yesterday.
- The Night That Never Ends: A variation — instead of blotting out the sun, the Slitheen are trying to drain the sun of its energy.
- Parental Bonus: Maria's divorced mother asks her ex-husband if she can have the double bed size duvet as he won't need it having a single bed. Her mannerisms and delivery of this line is enough to make older viewers think she's making fun of his sex life.
- School for Scheming: The Slitheen have set up bases within schools worldwide to power their sun-draining machine.
- Second Episode Substitute: Clyde replaces Kelsey from the pilot as the snarky and obnoxious secondary companion.
- Shout-Out: "Let's have a High School Musical moment. A group hug will sort everything out."
- The science teacher Slitheen mentions the children's rhyme that little girls are made from "sugar and spice and all things nice."
- Toilet Humor: Luke doesn't understand it.
- Two of Your Earth Minutes: The teacher who's really a disguised Slitheen refers to "your... our main electrical supply".
- The X of Y
