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 [[SincerityMode 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 [[Recap/DoctorWhoNSS1E5WorldWarThree their family]].
* AdventureRebuff: Both Sarah Jane and Maria try to make Clyde go away for his own good. [[CaptainObvious It doesn't work]].
* BlandNameProduct: Clyde's Wolverine brand body spray, a play on the real brand "Lynx".
* ContinuityNod: [[Recap/DoctorWhoNSS1E4AliensofLondon Slitheen in]] [[Recap/DoctorWhoNSS2E3SchoolReunion Downing Street]].
* EvenEvilHasLovedOnes: [[spoiler:the slitheen beg Sarah Jane and the other's to let his son live]]
* EvilTeacher: The Slitheen pose as teachers [[spoiler: worldwide]] during their revenge plot.
* FatBastard: The Slitheen, as usual.
* FridgeHorror: [[spoiler: Korst, The young Slitheen child, had to have killed Carl, a smart school boy only around the age of Maria and Clyde, for his disguise.]]
* HoldYourHippogriffs: "Oh, for the love of Clom!"
* IncestSubtext: Between Glune, the headmaster Slitheen, and Kist, the science teacher Slitheen, [[FridgeBrilliance which might help explain why]] [[IncestIsRelative the Slitheen are so screwed up]].
* LargeHam: All of the Slitheen.
* NiceJobBreakingItHero: 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 thr- [[YoungerThanTheyLook oh.]]
* NightmareFuel: The Slitheen, [[spoiler: having murdered people worldwide for their disguises.]]
* SecondEpisodeIntroduction: Clyde.
* SchoolForScheming: [[spoiler: The Slitheen have set up bases within schools worldwide to power their sun-draining machine.]]
* ShoutOut: "Let's have a ''HighSchoolMusical'' moment. [[SarcasmMode A group hug will sort everything out]]."
* TheNightThatNeverEnds: A variation, [[spoiler: instead of blotting out the sun, the Slitheen are trying to ''drain'' the sun of its energy.]]
* ToiletHumor: Luke doesn't understand it.