In Scotland humans survive in small tribes, forced high into the Highlands. They are starving as there is little grazing for sheep and they do not dare plow or plant crops for fear of the demons that fly through the air.

Then a messenger comes from America with a vision to save mankind—he requests that fifty men come with him back to the Psychlo mining camp near Denver, Colorado. The messenger is Jonnie Goodboy Tyler.

The Chief of the Clan elects one man in particular for this adventure—a veteran of many raids, and very learned—Robert the Fox.

Under the guise of working with a group of humans to mine for the villainous Psychlo Terl, Robert the Fox puts into action his skills in military tactics and plays a major role in executing the rebellion against the alien invaders.