Brigadier Lethbridge-Stewart asks the Doctor to investigate a mysterious murder near a new theme park called Space World. Together with Sarah Jane Smith and her photographer Jeremy Fitzoliver, the Doctor investigates the mysterious Parakon Corporation, which is not quite of this world.
- A Head at Each End: The Venusian Klakluk, according to one of the Doctor's anecdotes.
- Amusement Park: Spaceworld
- Continuity Nod: The Doctor tries to sooth the Gargan with the Venusian Lullaby, just like he did with Aggedor. He mentions his old teacher as well.
- Large Ham: Chairman Freeth, who makes a meal of every line he utters.
- Multipurpose Monocultured Crop: Rapine, a plant that's the source of everything from food to furniture to metal-substitute.
- Simpleton Voice: Jeremy, who is a rather facetious nincompoop.