Five years after the harrowing events on Xylos, Decurion Valerius and the First Cohort of the Nova Legio face an even greater threat: the K’Tharr Confederacy. These bio-aggressive entities are overwhelming Progenitor forces in the Tau Ceti Outer Rim, their unique biology proving resilient against Ascendancy technology and even compromising the effectiveness of the Dampening Fields. As the Progenitors’ war effort falters, the Nova Legio, their specialized human weapons, are thrust into the inferno of Veridian Prime and other besieged worlds to stem the K’Tharr tide.

Amidst the brutal grind of this new war, Valerius and Optio Livia—now an intelligence analyst with access to critical Progenitor data—must navigate not only the relentless K’Tharr onslaught but also the callous indifference and brutal machinations of their Progenitor masters, including the formidable Titus Prime. As secrets of their true origins and the Progenitors' manipulations continue to surface, and with the emergence of even more perfectly conditioned Primus-Born legionaries, the seeds of rebellion within the Nova Legio begin to sprout. Facing betrayals and impossible odds, a desperate plan is forged, one that could mean their ultimate destruction or ignite a true hope for freedom.