The Dragon's Egg: The Dragonslayer Series: Book Four of Four (Unabridged‪)‬

In the fourth and final book of the Dragonslayer series, Mandulane's army is poised to attack the Northlands in the name of a powerful god, but in truth Mandulane is using the act of spreading this new faith as a way to disguise his own personal greed and hunger for power.  

Astrid has succeeded in warning her beloved country of imminent danger, and the Northlanders scramble to set up a clever defense, never realizing a spy in their midst is poised to take critical information directly to Mandulane. 

Author's note: This series is written for adults but appropriate for ages 14 and up.