The Avenger of Thule — Arthur Wiederhold

The Avenger of Thule is rich in characters, action and plot. A young prince returns to his father's kingdom after a self-imposed exile, only to find it in the hands of a conquering horde. Determined to exact vengeance upon his enemies, Arka-Dal gathers up an army and forms alliances to do just that. Along the way, he discovers a box containing ancient books and runs afoul of a powerful sorcerer.