In Sigma Star Saga, Earth is under constant attack by the Krill, an alien race of beings that pilot living ships. The ships patrol the skies and upon encountering trouble they beam the nearest pilot into their control cavity to take over. The Krill's technology is fused onto the pilot, meaning that the brains of the ship - literally - are the pilots flying them.

Ian Recker, Earthman and ace pilot, infiltrates the Krill and gains their trust. His mission: to uncover their secrets while (he hopes) avenging the death of his crack squad of pilots, Sigma Team, who all perished during a particularly heavy Krill attack.

One man's hatred and pursuit of vengeance falters as he learns that the line between good and evil isn't so black and white…