The map of all things - Kevin J. Anderson

After terrible atrocities by both sides, the series of skirmishes between Tierra and Uraba has spread and intensified, erupting into a full-blown crusade and irreparably dividing the known world.

Now that the Uraban leader, Soldan-Shah Omra, has captured the ruined city of Ishalem, his construction teams discover a priceless ancient map that can guide brave explorers to the mysterious Key to Creation.
Omra dispatches his adoptive son Saan to sail east across the uncharted Middlesea on a quest to find the Key.

In Tierra, Captain Criston Vora sets out to find the fabled land of Terravitae. But Criston cannot forget his previous voyage that ended in shipwreck and disaster, and the loss of his beloved wife Adrea, who - unbeknownst to him - fights to survive palace intrigues and constant threats against her life in far-off Uraba. For Adrea is now the wife of the soldan-shah - the sworn enemy of Tierra . . .