Parts: 4
Writer: Terry Nation
Airdates: 1 September 1979 - 22 September 1979
Production Code: 5J

Doctor: fourth
Companions: the second Romana, K-9 mark two

Megalomaniac of the Week: Davros
Creature Feature: Daleks, Movellans

Story: The TARDIS materializes on a rocky planet, so naturally the Doctor and Romana - who has just grown tired of her old body and swapped it for a new one - go outside to explore. All they can find, aside from rocks, are the remains of a city. But travel on the planet's surface is dangerous, for quakes periodically rock the ground. Are they natural...or from some underground drilling operation?

As the Doctor and Romana explore, they see a ship land nearby. But when they approach, exploding shells are fired at them from somewhere, and they are forced to retreat. When they take refuge inside an abandoned building, the explosions and the drilling cause a slab of rock to fall onto the Doctor, who is pinned beneath it. Romana goes for help, only to find the TARDIS under a rockfall; and when she returns, the Doctor has vanished.

The Doctor has been taken by the people aboard the spacecraft - Movellans - who have a secret agenda for being on the planet...which, as the Doctor learns, is Skaro. Meanwhile, confronted by a threatening-looking man, Romana accidentally falls down a shaft and ends up underground - where a band of Daleks burst through a wall to discover her. But what are the Daleks drilling for on their own planet? What exactly are the Movellans doing on Skaro? And when the Daleks find what they are looking for, will it enable them to tip the balance of their ongoing war in their favor?