Martha Wells-Wheel of the Infinite torrent

Every night the Voices of the Ancestors - the Wheel's constructors and caretakers - brush the darkness away and repair the damage with brightly colored sands and potent magic. Each morning the storm reappears, bigger and darker than before, unraveling the beautiful and orderly patterns. With chaos in the wind, a woman with a shadowy past has returned to Duvalpore.
A murderer and traitor - an exile disgraced, hated, and feared, and haunted by her own guilty conscience - Maskelle has been summoned back to help put the world right. Once she was the most revered of the Voices, until cursed by her own actions. Now, in the company of Rian - a skilled and dangerously alluring swordsman - she must confront dread enemies old and new and a cold, stalking malevolence unlike any she has ever encountered