The Dorcons -the most powerful race in the galaxy -demand that the Alphans hand Maya over to them. Koenig refuses, until Moonbase Alpha is savagely attacked and invaded! Then, having let them take Maya he makes a desperate attempt to save her....
The arrival of the Alphans on another planet seems to cause a change in its atmosphere, setting off pollution and poisoning of the water. They meet Zoran, the sole survivor of the last exploratory force, who tells them that the planet is controlled by an immortal being - with whom Koenig must parley if he and his crew are to leave the planet alive.
Answering a distress signal, Commander Koenig is forced to crash-land his Eagle on Entra - moon of the planet Ellna - which turns out to be the planet's penal colony, and Koenig finds himself a prisoner of the beautiful Elizia and her equally beautiful prison guards.
Some subterranean miners start chanting for a planet that will cause the Moon to pass through a nebula deadly to those living at Moonbase Alpha.
Everyone on Moonbase is electrified by the arrival of a spaceship from earth. Everyone, that is, except Commander Koenig. Where the others see long-lost friends and relatives, he sees hideous aliens, bent on taking over the Moonbase...
A pretty, young Alpha technician dies a horrible and unexplained death. Dr. Russell's experiments reveal that one of the crew is possessed of paranormal mental powers and is trying to take control of Moonbase Alpha....