Shadowrise - Tad Williams, Orbit

As shadows threaten to consume the kingdom of Southmarch, Barrick Eddon, heir to March throne, battles his way across the sinister Shadowlands. He must journey through this dangerous, inhuman realm to fulfil a pact ? as this may be all that can prevent the atrocities of a full-scale war with the Twilight people of Qul-na-Qar. Princess Briony, Barrick's twin sister, finds herself in no less danger at the court of Tessis in Syan. When those close to her fall dead from poisoning, she is to learn the true extent of the betrayal surrounding her. Her only option is to flee, as all those in Tessis turn against her ? all, that is, except for one important ally. Meanwhile, the assault upon Southmarch has truly begun. Yasammez, the formidable head of the Qar army, has ordered the attack, believing that the pact between humans and Qar has been broken. Unless Ferras Vansen, Captain of the Southmarch Royal Guard, can convince her otherwise, the humans are sure to meet the dark end that has been promised to them ...