|Native Species:||Maths Masters|
Mathsville was a city located in a secret junction in Hilbert Space, accessible only though a collection of hidden logic gates, one of which was located on the planet Newer South Wales. The city was characterised by its incomprehensible geometries, where larger objects appeared to fit within smaller ones.
The Fourth Inspector's final quest before his metamorphosis was to locate Mathsville and travel there to thwart the Sergeant's mysterious plot to "collapse the wave function of the universe". The city's inhabitants, the Maths Masters, had to be convinced to stop tampering with the Schrödinger Equation, as their endless computations were playing into the Sergeant's hands.
The serial is best known for its "Non cogito, ergo non sum" ending. After the traditional climactic chase, the critically wounded Inspector confronts the Sergeant and defiantly demands, "Are you going to come quietly?" The Sergeant replies, "I think not."—and immediately disintegrates in a puff of logic.
The fact that the Sergeant never before or since displayed the powers or universal ambitions that he did in this plot-arc led to the popular fan-theory that he was either receiving backing from or being impersonated by the Orange Warden.