The "Doctor" (Tom Baker) is fiddling about with the TARDIS when in walks "Romana" - except, well it isn't her. Or is it? Can she regenerate too? Appears so and so now Lalla Ward picks up the slack. Luckily, there's still the old quarry to set this story in as they emerge in the middle of an inter-galactic scuffle between the "Movellans" and their (and everyone else's) arch enemy - the "Daleks". "Tyssan" (Tim Barlow) represents the indigenous human population who are being used by the latter to excavate deep under the surface - but why? Well it doesn't take our time travelling duo long to realis...