At the edge of our Milky Way, an unreal space battle rages. Spaceships of the Invisible, with whom Perry Rhodan has previously encountered on the planet Barkon, are attacking bizarre-looking ship constructions of unknown origin. Soon, Terrans and Arkonides become embroiled in the fighting. The strangely designed spaceships, referred to by humans as Fragment Ships, belong to a mysterious robot civilization. The robots seem to hate all organic life and are launching increasingly violent attacks against the Milky Way. Terran task forces discover that the robots have an organic component. Positronic command units and organic cell plasma simultaneously control the robots, known as Posbis. Fargo and Everblack, two Posbi worlds located in the void between galaxies, are discovered by the Terrans. While Perry Rhodan is on the trail of the Posbis' mystery, an invasion fleet of Fragment Ships floods the globular star cluster M 13, threatening to annihilate Arkon. Will Perry Rhodan's desperate plan to stop the Posbis succeed?.