The Machines are on the move to eradicate the presence of intelligent life in their space.
The Empire of New Terra, newly come to this space, have discovered that the Death Machines they had created centuries before are still in existence, and they are out to destroy humanity. Exploration Command, with reinforcement by the Fleet, was able to stop them from destroying Klassek and Bolthole, but those were just the initial scouting forays. This time the Machines are coming in earnest, and they're bringing overwhelming force with them, including more of their almost indestructible planet killers. It is a battle of extermination for the Empire and their Klassekian allies. The Machines are tireless and implacable, and the Empire is already stretched to the limit on all fronts. But organic intelligence has some abilities the Machines lack, and they hope that with some mighty weapons and some brilliant tactics they can carry the day. If not, the Machines will continue on their crusade of death in the Persius arm and beyond.