Books like The Dark Citadel

A slave boy named Darik falls in with a pair of spies as the great city of Balsalom comes under siege by the armies of a dark wizard. They flee west to enlist the aid of griffin riders, an order of wizards, and a band of ascetic knights to come to the city's defense.Meanwhile, a young queen named Kallia leads a heroic struggle to keep both her city and body free from the dark wizard's cruel embrace. After a treacherous attack opens Balsalom to the armies of the enemy, Kallia assembles an unlikely alliance of palace servants, barbarians, and jealous merchants to retake her city before its people are led away in chains.The Story continues in Book #2: The Free Kingdoms.