If not for the intervention of the insectoid beings called the T'lack, the Faceless War would have ended with the extinction of Humanity and its Sibling Species. That intervention came at a great cost for the T'lack. No one knows or understands Humanity's debt to the T'lack better than Jan Costa, who paid his own terrible price at the end of that war.
Now the T'lack are themselves in grave danger, facing a devastating civil war between rival factions and threatened by a mysterious race of beings on the far side of T'lack space.
Jan Costa leads a multi-species expeditionary force into the unknown, seeking to save his alien friends both from themselves and the new threat they have aroused. What he discovers out beyond the frontier will change everything, with the very existence of the T'lack hanging in the balance.