L. E Modesitt

"You can't militarize space. This one rule has led to decades of peaceful development of space programs worldwide. However, increasing resource scarcity and a changing climate on Earth's surface is causing some interested parties to militarize, namely India, the North American Union, and the Sinese Federation. The discovery of a strange artifact by Dr. Alayna Wong precipitates a crisis. What appears to be a hitherto undiscovered comet is soon revealed...

When voice teacher Anna Marshal wishes she could be anywhere besides Ames, Iowa, she is magically transported to the world of Erde where singing is magic, and she becomes the most powerful sorceress there.

Saryn, Arms-Commander of Westwind, is dispatched to a neighboring land, Lornth, to seek support against the Gallosians while the trading council of Suthya forms a secret alliance with Gallos against Westwind.