The robotic legions of the First Imperium burst into human space, destroying everything in their path. Their antimatter-powered fleets drove back the desperately defending human forces, seizing world after world. Directed by the maniacal Regent, the enemy pressed forward with one goal – the destruction of mankind.

The Superpowers of Earth, bitter enemies for over a century, have at last banded together to face the threat from outside. Their combined forces have fought stubborn delaying actions to buy time, but they couldn't stop the relentless onslaught. Now the Rim has fallen, and the heart of human space lies before the invaders.

On three worlds, mankind will make its stand, and all the power Earth and its colonies can muster has been gathered there. Three worlds – Sandoval, Garrison, and Samvar. The Line.

Erik Cain grimly leads his veteran Marines and their new allies to Sandoval, to fight and to hold that world against anything the enemy throws at it. But Cain plans more than just a defense; he intends to annihilate the enemy forces…and he’ll sacrifice anything to win the ultimate victory. Even his soul.