Tanner and his Flame Bird, Firepos, have met a companion, a Chosen Rider to a ferocious wolf-Beast. Together, they must race to locate the missing pieces of the Mask of Death. If evil Derthsin gets the mask first, Avantia will be destroyed in a reign of fire. Who will Tanner meet next on his journey? And what horrors lurk in the Hidden Mine's endless tunnels?