Warlock of the Valley - Heroes of the Valley, #4

The Remordan Valley is at peace. Greenness and life, quickened by the long days of summer, has begun healing over the scars of the Spring War. Cities rise anew. And with the perils past, heroes have gone their separate ways, back to businesses, to journeys of discovery or long-delayed responsibility. But with the first whispers of autumn, darkness creeps back into the Valley. A former wizard's apprentice is not all she seems.
And a millennia-old war criminal thinks she belongs to him. With powers from beyond the grave, he intends to steal her back. The Heroes of the Valley don't leave their own behind. The wizard will return for the apprentice he raised from infancy, with the half-elf warrior-priestess at his side. The Legion veteran and his hobgoblin partner are always spoiling for a fight. And the gnome politician can always be counted on to raise an army, or hell. But none of them realize the true depths of their danger - this time, it's not goblins or barbarians. There's a Warlock loose in the Valley.