Ancient Peace, An (Peacekeeper, 1)

Someone is searching for the lost weapons of the H'san: powerful enough to destroy entire planets. Though the H'san gave up fighting long ago, the reappearance of their lost weapons would no doubt lead to a devastating war. It's up to Torin Kerr and her team to fix this problem before it explodes. But the more Torin learns about the relationship between the Elder and Younger races, the more she fears war might be unavoidable.