|Original air date||
4 September 1976
An Eagle is sent onto the surface of the planet Psychon, which has titanium, needed for repairs to the Alpha Base. It fails to return and is used by Psychon scientist Mentor as bait with which to entice other members of the Alphan crew onto the planet. Mentor is building a computer but it will be fuelled by the living brains of humans, and he has his eye on those of the Alphan crew. Fortunately his daughter, the shape-shifting Maya, does not share her father's views and is on the side of the Alphans.