An irresistible force draws the Tardis to the barren surface of Frontios, where in the far future the last surviving humans cower amongst the ruins of their wrecked spacecraft. Under constant threat from lethal meteorite bombardments, few of the doomed colony members realise that the ground of Frontios itself opens up and devours the unwary. Not permitted to assist, the Doctor’s attempt to leave is thwarted when the unimaginable occurs: the Tardis is utterly destroyed.
 
All the while, burrowing undetected below the planet’s crust, sickening alien parasites prepare a gruesome and final fate for all humanity...