
Leela (Louise Jameson) made her debut appearance in The Face of Evil (1977). Part of the Sevateem, a warrior tribe descended from a crew of an Earth ship crash-landed on an unknown planet, she was highly intelligent, curious, stubborn, alert and armed herself with a large knife and poison Janis thorns.
The fourth Doctor (Tom Baker) tried to explain to Leela, the working of the TARDIS using the analogy of how a larger cube can appear to be able to fit inside a smaller one if the larger cube is farther away, yet immediately accessible at the same time – did you get that?