Stig is contesting the annual Maktig competition to decide Skandia's greatest warrior. But an unexpected visitor arrives with a request Stig, Hal and the brotherband can't refuse- a rescue mission of epic proportions.<br> <br> Pirates have kidnapped the son of the Empress of Byzantos, a city-state far to the south. The brotherband sets sail to recover the boy, only to find that the pirates' fortress seems impenetrable, sitting atop towering cliffs above the deep lagoon - the caldera - of a volcanic crater.<br> <br> Culminating in a battle for survival on the high seas, <i>The Caldera</i> sees the Herons take on one of their most difficult missions yet as the fate of an empire rests on their shoulders.<br> <br> BONUS <i>RANGER'S APPRENTICE</i> STORY INSIDE!