TRIAL BY FIRE! Robert Parker ventures into the vast unknown to study new species of plant and animals in the name of science. And he's thrilled when a young half-breed named Zach King invites him back to his secluded valley in the Rocky Mountains - a valley teeming with wildlife that no naturalist has ever explored. But Parker's about to find out he's not the only newcomer. Three murderous prospectors have heard there's a fortune in gold on the Kings' land, and they'll do anything to get their hands on it. They've heard how tough the Kings are, and they're well prepared for that. But they haven't counted on the grit of one determined greenhorn...