Charles Sheffield 
Transcendence [EPUB ebook] 

The Zardalu were the greatest menace ever known to the worlds of the spiral arm, enslaving entire races and exterminating others, guided by an unswerving belief in their own supremacy. Then their slaves rose up against them, and for eleven thousand years the Zardalu had been extinct and the spiral arm had known a kind of peace.But now the Zardalu are back . . .The search for the Builders, the legendary alien race whose unfathomable constructs continued to perplex scholars and explorers alike, had 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 found the Zardalu – just a few who had been trapped in stasis all those millennia, held there for purposes known only to the Builders. And in the struggle that ensued the Zardalu had been set loose, transported by Builder technology to to galactic parts unknown – free to ravage any world and any race within their grasp. The only chance to eliminate the Zardalu threat was to find them and wipe them out before they had time to breed back up to strength and once again threaten civilized beings everywhere. The problem was that no one believed the story. Only Darya Land and her companions had actually seen the aliens – and no evidence existed to support their claims. And so the course seemed clear: get a ship themselves and search out the Zardalu. But the way would not be easy. Even once they managed to locate the Zardalu, they still had the Builders to deal with. For the closer they got to their quarry, the more clear it became that the Zardalu and their world were closely entwined with the fate – and the plans – of the Builders themselves.