Book of War (Diadem Series)

When Helaine was whisked away from home, she never got a chance to say goodbye. Now she's homesick and worried about her family. As the daughter of prominent Lord Votrin, Helaine knows her sudden departure ruined her father's plans to forge an important alliance with another township-an agreement that promised Helaine's hand in marriage.

Score, Pixel, and two unicorn friends accompany Helaine to Ordin-a medieval planet of high-brow nobles, oppressed peasants, and endless battles over land. Upon finding her home, Castle Votrin, under siege by the Border Lords, Helaine vows to make it up to her father. With help from Jenna-a pretty, spell-working healer with a crush on Pixel-they struggle against angry villagers, giant insects, and pillaging soldiers to find a way to save Helaine's home and her family honor.