Ghost in the Storm. The Ghosts, #4

CAINA AMALAS is a Ghost nightfighter, one of the Emperor's elite spies and assassins. And though she remains anonymous, already legends grow around her. Whispers speak of the Ghost nightfighter who stopped the fire of the gods from consuming Rasadda, who defeated sorcerers of terrible power, who liberated slaves and threw down cruel lords. Yet now the storm is coming to claim her... ARK spent five long years hunting for his missing wife and son.
Now, at long last, he has found them again. When the storm comes, he will do anything to save them. No matter what the cost to himself... KYLON is a stormdancer of New Kyre, master of the sword, wielder of the sorcery of air and water. The youngest man ever to claim the title of stormdancer, he will fight for the honor of his city and his sister. Even if he is doomed to fail... REZIR SHAHAN is an Emir of Istarinmul, a man of cruelty and power, a tyrant who rules over his slaves with a rod of iron.
For too long the commoners of the Empire have defied their rightful masters. When the storm comes, he will teach them to wear a slave's collar... ANDROMACHE is one of the nine archons of New Kyre, her lineage ancient, her authority vast. For the honor of her city, she will bring the storm of war to the Empire. And when she does, her true master will reward her with dark power beyond imagining.