in the tardis, the first doctor, ian, barbara and vicki are huddling around the time-space visualiser, a television-like souvenir from their recent adventure at the space museum, which can pick up on any past event in the whole of time and space. the tardis then lands. ian and vicki leave to explore the desert wilderness. they find an ancient trap door in the sand. inside, they are trapped — and become hunted by hostile tentacle creatures called mire beasts.