The Alphans fall into the grasp of the despotic Mentor, an alien scientist trying to restore his ravaged world to its former glory. His biological computer requires the energy obtained from living brains to complete his task. When captured, Koenig is offered a choice: surrender the Alphans to a horrifying living death or face complete annihilation. Mentor's daughter Maya, who is a metamorph and from whom Mentor has concealed his actions, may be able to aid the Alphans.

Colonel Foster is tried and sentenced to death after a security leak is traced to him.

Yung-Star devises a way to make the Cubes more powerful by combining them. Zelda forms a group of them into a gun and threatens to destroy a newly constructed dam. Meanwhile, Tiger finally loses patience with the Zeroids and orders Zero to give them a new, 'standardised voice', but regrets his decision when all the Zeroids speak with the Sergeant Major's voice.

Whilst out in the desert Tex Tucker finds and shelters an Indian boy and is rewarded with four magic feathers by the boy's grandfather. Two of the feathers make his dog (Dusty) and horse (Rocky) speak whilst the last two control Tex's two guns. Tex decides to create a town called Four Feather Falls and the townsfolk make him Sheriff.

Fireball XL5 intercepts a missile launched at Earth. Landing on Planet 46, Zodiac and Venus are captured by the villainous Subterrains – who promptly launch a second missile with Venus on board.

Agent X-2-Zero frees the former dictator El Hudat from the Marineville brig by replacing him with his twin brother.

Following the events of Lunarville 7, Scarlet, Blue and Green return to the Moon to destroy the Mysteron's newly completed base in the Humboldt Sea.

A wealthy widow's daughter is kidnapped and Harry is required to drop off the ransom money.

Chris attempts to broaden the remit of the Randomiser by reviewing an episode of a non-Gerry Anderson series made by someone who used to work for Gerry Anderson and who used this particular episode to pay tribute to his days working on Gerry Anderson shows. The experiment backfired horribly.

Whilst exploring a bizarre asteroid, Koenig is detained and replaced by a double which directs Alpha to direct most of its energy at the asteroid. Some of the crew react negatively at his double's dictatorial behaviour.