Circle of the Moon (Sisters of the Raven, No. 2)

"Couldn't put it down until the end ... a great fantasy." (MyShelf.com)
Returning to the wondrous world of Sisters of the Raven, Barbara Hambly presents a suspenseful new story of a fledgling group of women who must develop their own magic abilities - before the demons of the past return to kill again...
A MAGIC WOMAN'S WORK IS NEVER DONE
The laws of magic have changed- no one knows how and why. And with that change, new perils havearisen: deadly water monsters from the depths of the Seven Lakes and a plague of madness in the desert. In the strongholds of human safety, anger and greed bloom as nobles and landchiefsfight for power. Raeshaldis, the only woman formally trained in the old systems of male magic, allies herself with the beautiful concubine Summerchild to found the Circle of the Moon - a motley group of women whose powers are unknown and unreliable. Faced with an attempt by the landchiefs to oust the king and with the efforts of her family to re-enslave her, Raeshaldis must play a deadly guessing game with untested spells and questionable allies, while an even more terrible threat awaits...