The latest saga in the New York Times bestselling world of Osten Ard concludes in the fourth and final Last King of Osten Ard novel.

The Hayholt is in flames. Once the home of the immortal Sithi, now capital of the kingdom of men, the fabled castle has been set ablaze by vengeful Norns. And as the world is distracted by this devastating attack against humankind, the Norns' deathless witch-queen Utuk'ku reaches out to seize the fateful, ogre-haunted valley called Tanakirú—the Vale of Mists.

Fooled by the Norn Queen’s trickery, Simon and the Sitha Jiriki must now leave the burning castle behind to race to the forbidden valley. But the undead spirit known as Ommu the Whisperer travels with them, hiding in the body of Simon's granddaughter Lillia. Meanwhile, Queen Miriamele hurries to save the Hayholt and capture the treacherous noble Pasevalles, but arrives to discover the castle is on fire and the traitor has escaped.

And in Tanakirú, the bond between Prince Morgan and Nezeru, a renegade Norn, has become something deeper and stranger than either of them could have anticipated. Accompanied by Morgan's troll friends Qina and Little Snenneq, they journey ever deeper into heart of the valley’s mystery, encountering wonders and horrors, only to come face to face at last with the ancient secret that has kindled the Norn Queen's war—a secret that threatens to destroy immortals and humans alike.