The Princess, the Witch and the young Dracolich

After an incident involving a Necromancer and his legions of dead invading a small settlement, the castles ruler a young princess ally's a witch and a newly created dracolich to adventure to find the invading forces and defeat them, along the way the setting begins to change, the dead arisen and the lands twisted, what was a journey to redeem their people becomes a mission to save the lands and quite possibly the world itself...