Earth has managed to recapture the Sol system from their Horvath conquerors and begin entering the galactic millieu. But when the Rangora Empire rapidly crushes humanity's only ally it becomes clear the war is just beginning, and Troy (a two trillion ton nickel-iron battlestation) is humanity's best hope of survival.

With the help of some alien technology, the humans on two worlds had fought back the ravening Posleen hordes. Now the survivors of Barwhon and Diess Expeditionary Forces take time to regroup and renew themselves, while on Earth they build a new force of recruits, as the Posleen hordes once again prepare to descend on Earth.