The body of Anton Zoref is invaded by an unknown life force. The man soon manifests an uncontrollable ability to absorb energy. As the Alphans struggle to understand this mysterious force, Zoref's need becomes insatiable. Driven by instinct, he makes his way to the greatest source of energy on Alpha: the Nuclear Generating Plant.

The automated Earth space probe Voyager One is approaching the Moon. With the radioactive exhaust from its engine certain to extinguish all life on Moonbase, the Alphans try to gain control and shut down the drive. Help comes when the probe's designer is found living on Alpha under an assumed name. However, Voyager is being followed by alien ships seeking revenge.