Only the past can save humanity's future. Earth fell with little resistance, but scattered pockets of free humanity, mostly on research installations and a remote colony, refuse to let the mother world perish. Careful to avoid detection lest they be overcome by the aliens' superior numbers and firepower, scientists on outpost Horizon concoct a desperate plan to plunder the past for people and resources in the hopes of preserving the future of the human race. Valerius, a former Roman legionnaire turned commander of earth's reinvasion force, has to overcome millennia of human differences in order to forge a force from throughout history that is capable of dislodging the invaders. With the need to avoid alien detection, preserve the timeline, and fight the rising internal division, he hardly has time to acclimate to a post scientific-revolution age, or even figure out how to meet the woman of his dreams. Scintillating space battles, ominous aliens, time travel adventures and an array of colorful characters unite in this roller-coaster ride that takes many twists on its way to illuminating the human soul and one man's courage to persevere the human race.