General Jake Taylor and his army of cyborg soldiers are veterans of Erastus, a planet so brutal, so hellish, it is called Gehenna by the men sent to fight and die there. He and his comrades battled for years in the most appalling conditions human beings have ever endured, believing the entire time they were protecting Earth from bloodthirsty alien monsters. But it was all a lie, the cynical propaganda of the totalitarian regime that rules over all mankind.
The alien Tegeri, and their bio-mechanical soldiers Taylor's men call the Machines, were the victims, targeted by a regime that needed an enemy to consolidate its absolute rule over mankind. For decades, men like Taylor and his soldiers were the aggressors, unwittingly fighting an unjust war. But when the Tegeri chose Taylor as their contact and finally told him the horrible truth, he rallied the veterans of Erastus for a new battle, one to free Earth from its self-appointed masters.
Taylor's soldiers begin the long campaign back to Earth, toward a reckoning with the brutal government they are sworn to destroy. The heart of this force is the Ten Thousand, surgically-altered Supersoldiers, products of an experimental enhancement program, and the first of their kind. But they are not the last, and on the planet Juno they will meet their counterparts, the Black Corps, a force created by Earth's government specifically to destroy them. The Black Corps outnumbers Taylor's soldiers 2-1, and they have a vast advantage in supply and logistical support. But Taylor's men are veterans of the furnace of Gehenna, and they don't die easily.
But there is more at stake than the freedom of humanity, greater consequences to their fight than even Taylor can imagine. For there is another alien race, one shrouded in legend and myth, known to the Tegeri only as the Darkness. Long ago the Darkness.