The Doctor with the Drahvins

The Doctor, Vicki and Steven Taylor arrive on an eerily silent and arid planet in Galaxy 4, where they meet the occupants of two crashed spaceships: the beautiful Drahvins and the hideous, reptilian Rills.

They also encounter curious small robots, which Vicki names Chumblies. It is unclear, at first, whether the robots are hostile and so the time travellers are wary of them. One of the robots is disabled by a party of Drahvins - who The Doctor learns are from the planet Drahva that is also in Galaxy 4.

After being captured by Drahvins, The Doctor and his companions soon realise that the Drahvins are mindless, female cloned soldiers terrorised by the warlike matriarch, Maaga - who treats her other warriors with bullying contempt.

The Drahvins

Maaga also paints a picture of the Drahvins as the attacked species in the scenario, but The Doctor has witnessed some of the Drahvin aggression and is clearly not convinced.

She explains that both spaceships were damaged when the Drahvins precipitated a confrontation in space, but whereas the Rills' is almost ready to take off again - having been repaired by their robot drones, the Chumblies - the Drahvins' spaceship is irreparable.

A Chumbley

Then it is discovered that the planet is on the point of disintegration and that Maaga and her warriors are keen to capture the Rill spaceship so that she and the rest of the Drahvins can escape. But instead of the 14 days the Drahvins think the planet has left before it is destroyed The Doctor calculates that they only have two days before they all have to leave. The Doctor tries to keep this new finding from the Drahvins, but Maaga reveals her true colours and forces the truth from him.

With Steven held as hostage, to ensure their co-operation, The Doctor and Vicki are sent by the Drahvins to try to seize control of the Rill spaceship. However, while in the Rills' spaceship, The Doctor discovers that the Rills are in fact a very advanced species. Confounding expectations, the Rills, who the Drahvins are at war with, prove to be friendly, compassionate explorers.

The ugly, horned, ammonia-breathing Rill explains that they have offered to take the Drahvins away with them but Maaga has refused, preferring to maintain the state of war she began when the Drahvins shot down the Rill’s craft. The Doctor tells the Rills of the true life remaining in the planet and promises to help them escape, by allowing them to draw power from the TARDIS in order to refuel and escape.

The Doctor and Vicki

The Doctor and Vicki then return to the Drahvin ship but find Steven unconscious after Maaga had tried to kill him. They manage to rescue him just in time and, with the aid of a Chumbley, they manage to return to the TARDIS.

Learning that the Rill’s are about to escape Maaga leads the Drahvins in a final assault on the Rill craft. But the Chumblies defend the Rill’s ship long enough for it to power up and leave the planet leaving the Drahvins behind to perish on the dying world.