The TARDIS materialises on board a Minyan ship, the R1C, commanded by Jackson. To the Minyans the Time Lords are Gods. In the past the Time Lords helped the Minyans build an advance civilisation. Minyos is now dead, destroyed by warfare.
The crew are on a quest to find the P7E which contains the gene bank of the entire Minyan race. The P7E is eventually located - at the centre of a planet which had grown up around it.
Descendants of the original crew, and are ruled by the computer which has been programmed to protect the race banks, and robotic Seers have survived.
Jackson thinks he has managed to obtain the race bank, but he has been tricked and in fact has fission grenades. The Doctor discovers the deception and manages to obtain the real race bank, and tricks the Seers into taking back the grenades. The explosion destroys the planet, and the P7E, allowing the R1C to blast free toward Minyos II, with the Minyan descendants on board.
- Leela: Louise Jameson
- Voice of K-9: John Leeson
- Jackson: James Maxwell
- Tala: Imogen Bickford-Smith
- Orfe: Jonathan Newth
- Herrick: Alan Lake
- Idmon: Jimmy Gardner (2-4)
- Idas: Norman Tipton (2-4)
- Tarn: Godfrey James (2-4)
- Rask: James Marcus (2-4)
- Guard Klimt: Jay Neill (2)
- Ankh: Frank Jarvis (3-4)
- Lakh: Richard Shaw (3-4)
- Voice of the Oracle: Christine Pollon (3-4)
- Naia: Stacey Tendeter (3-4)
|BBC 1||470. Part One||Saturday, January 7, 1978 6:25 PM - 6:50 PM||8.9M||65%|
|BBC 1||471. Part Two||Saturday, January 14, 1978 6:25 PM - 6:50 PM||9.1M|
|BBC 1||472. Part Three||Saturday, January 21, 1978 6:30 PM - 6:55 PM||8.9M|
|BBC 1||473. Part Four||Saturday, January 28, 1978 6:30 PM - 6:55 PM||11.7M|
- Television Centre Studio 3
- Television Centre Studio 4
- Television Centre Studio 8
Details of the extras who appear in this story are unavailable.