Conquerors' Legacy — Timothy Zahn

The Zhirrzh are preparing a massive attack against Earth. Meanwhile, Lord Stewart Cavanagh desperately searches for a defense against their devastating arsenal. As both humans and Zhirrzh gird for all-out war, a handful of individuals from both races discover the explosive catalyst behind the approaching holocaust--a misunderstanding so tragic and profound it has brought two mighty civilizations to the brink of mutual extinction. But there are subtle and dangerous forces at work whose goal is to spark an apocalyptic war--and the efforts of the small band of humans and Zhirrzh may be too little and too late to avert disaster....