Киз Грег: Elder Scrolls Novel. Lord of Souls

Reeling from a devastating discovery, Prince Attrebus continues on his seemingly doomed quest to obtain a magic sword that holds the key to destroying the deadly invaders. Meanwhile, in the Imperial City, the spy Colin finds evidence of betrayal at the heart of the empire - if his own heart doesn't betray him first. And Annaig, trapped in Umbriel itself, has become a slave to its dark lord.