blind, non-humanoid robots, dubbed "Chumblies" by Vicki. Before the trio decide whether the Chumblies are hostile, one of the robots is disabled by an all-female party of cloned blonde Drahvin warriors from the planet Drahva in the same galaxy as the silent planet, Galaxy 4. The Drahvins are dominated by their cruel leader, Maaga (Stephanie Bidmead), who treats her simple-minded subordinates with bullying contempt. The Drahvins are at war with the reptilian Rills, the masters of the Chumblies, and both races have crashed spaceships on this planet. According to the Drahvins, the planet will be destroyed in 14 planetary cycles and, with their ship irreparable, Maaga and her warriors seek to capture the Rill ship, which they believe has been made functional again. Maaga describes the Drahvins as the victims of the conflict with the Rills, but the Doctor has witnessed some of the Drahvin aggression and is not convinced. Using the TARDIS, he calculates the planet will break up in just two days' time. The Doctor tries to keep this new finding from the Drahvins, but Maaga forces the truth from him at the point of a gun. 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 ship. The Doctor works out that the ammonia-breathing Rills (voiced by Robert Cartland) are a very advanced species: when he meets one, he is impressed, particularly by their use of telepathy. The huge and impressive, horned warthog-like Rill explains that they have offered to take the Drahvins away with them but Maaga has refused, preferring to maintain a state of war. The Doctor tells the Rills of the true life remaining in the planet and promises to help them escape, since the solar energy converters on the Rill craft have not gathered enough power to effect a lift-off. The Doctor and Vicki return to the Drahvin ship to find Steven unconscious after Maaga has tried to kill him by leaving him in a depressurised airlock. They all return to the Rill vessel, where the Doctor successfully develops a power converter linked to the TARDIS, which charges the Rill craft. Maaga leads the Drahvins in a final assault, but the Chumblies defend their ship long enough for it to power up and leave the planet. A Chumbley helps the Doctor, Vicki, and Steven to return to