Commander Grant and his crew have escaped from Earth into deep space, dragging behind them a fleet of invading alien ships in a desperate attempt to give humanity's beleaguered defenses a chance to regroup. With their enemy closing in, they plunge headlong into the abyss and find themselves on the far side of the universe, face to face with an oddly familiar alien ally who is intently interested in their survival.
The Lyran race has spent millennia conquering the stars but have finally met a foe which they cannot face. They have not been idle, however, and have made ready for the time when a warrior would emerge from the darkness and lead their civilization to victory.
But nothing in war is as simple as it seems.