A group of gold-skinned aliens known as the Axons land on Earth and offer wondrous technology in exchange for fuel. The Doctor, however, isn't fooled, uncovering the Axons' true nature and once again facing his archenemy the Master...
| Actor | Role |
|---|---|
 Jon PertweeThe Doctor | The Doctor |
 Katy ManningJo Grant | Jo Grant |
 Nicholas CourtneyBrigadier Lethbridge-Stewart | Brigadier Lethbridge-Stewart |
 Richard FranklinCaptain Mike Yates | Captain Mike Yates |
 John LeveneSergeant Benton | Sergeant Benton |
 Roger DelgadoThe Master | The Master |
| PPaul GristBill Filer | Bill Filer |
| PPeter BathurstChinn | Chinn |
| FFernanda MarloweCorporal Bell | Corporal Bell |
 Donald HewlettGeorge Hardiman | George Hardiman |
| DDavid SavileWinser | Winser |
| DDerek WarePigbin Josh | Pigbin Josh |
 Bernard HolleyAxon Man | Axon Man |
| MMichael Walker1st Radio Operator | 1st Radio Operator |
| DDavid March2nd Radio Operator | 2nd Radio Operator |
| PPatricia GordinoAxon Woman | Axon Woman |
| JJohn HicksAxon Boy | Axon Boy |
| DDebbie Lee LondonAxon Girl | Axon Girl |
 Tim Pigott-SmithCaptain Harker | Captain Harker |
 Kenneth BendaThe Minister | The Minister |
| RRoyston FarrellTechnician | Technician |