Parts: 4
Writers: Bob Baker, Dave Martin
Airdates: 13 March 1971 - 3 April 1971
Production Code: GGG
Megalomaniac of the Week: the Master
Creature Feature: Axons
Special Guests: UNIT (the Brigadier, Benton, Yates)
Story: Snow and fog blanket the southeastern coast of England as a spacecraft approaches the Earth. When threatened by a fleet of missiles launched by the military, the craft disappears, only to turn up buried in the earth near Britain's main power station. Curious passersby are snagged by an organic tentacle and pulled into the craft, where they are analyzed...and, if they prove to be unworthy of further study, killed.
When the Doctor, Jo and UNIT arrive on the scene, they find that the occupants of the craft are transmitting a distress signal. The Doctor leads the way into the ship, where four golden-skinned humanoids await them. The aliens - known as Axons - explain that their planetary system was crippled by solar flares and they are in desperate need of nutrients and energy. The Doctor finds reason to doubt their claim when, in return, they offer the magical mineral axonite - able to absorb and reconfigure all forms of energy.
But other members of the Doctor's party are heavily swayed by the promise of such riches, which could end the world's hunger problem by enlarging the food supply. While some attempt to set up a monopoly on axonite, the Doctor does some more investigating. His findings lead him to a horrific discovery about the Axons...and the fate of the Earth.