Ghost in the Stone - The Ghosts, #5

Caina Amalas is a Ghost nightfighter, an assassin and spy of the Emperor, and her cunning saved the city of Marsis from a brutal invasion. Now she must keep the war from becoming worse. The nobles of the Imperial city of Cyrioch plan to revolt, and assassins stalk the high lords of the Empire. Only Caina stands between the Empire and a ruinous civil war. But Caina faces a far more dangerous enemy than mere assassins.
A enemy that whispers from the darkness of her own mind...