The search for the Builders, the legendary alien race whose unfathomable constructs continue to perplex scholars and explorers alike, has led Builder expert Darya Lang, adventurer Hans Rebka, and treasure hunters Louis Nenda and Atvar H'sial to an unknown Builder artifact far outside the spiral arm. There they find the Zardalu, once the greatest menace ever known to the worlds of the spiral arm, enslaving entire races and exterminating others, guided by the unswerving belief in their own supremacy.

The only chance to eliminate the Zardalu threat is to find them all and wipe them out before they have time to breed back up to strength and once again threaten civilized beings everywhere. But the way will not be easy. Even if they manage to locate the Zardalu, they still have the Builders to deal with. For the closer they get to their quarry, the clearer it becomes that the Zardalu and their world are closely entwined with the fate, and the plans, of the Builders themselves.