"The day I was born, I saved the world. Now I've helped to destroy it."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.
— Luke Smith
- Adventure Rebuff: Both Sarah Jane and Maria try to make Clyde go away for his own good. It doesn't work.
- Bland-Name Product: Clyde's Wolverine brand body spray, a play on the real brand "Lynx".
- Continuity Nod: Slitheen in Downing Street, which happened in "Aliens of London" and "World War Three", and Sarah Jane learned about in "School Reunion".
- 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.
- 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.
- Hold Your Hippogriffs: "Oh, for the love of Clom!"
- Incest Subtext: Between Glune, the headmaster Slitheen, and Kist, the science teacher Slitheen, which might help explain why the Slitheen are so screwed up.
- Large Ham: All of the Slitheen.
- 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 was born yesterday.
- Second Episode Introduction: Clyde.
- School for Scheming: The Slitheen have set up bases within schools worldwide to power their sun-draining machine.
- Shout-Out: "Let's have a High School Musical moment. A group hug will sort everything out."
- The Night That Never Ends: A variation — instead of blotting out the sun, the Slitheen are trying to drain the sun of its energy.
- The X of Y
- Toilet Humor: Luke doesn't understand it.