In the 24th century, Cree Indian geologist Keltyn SparrowHawk is sent to Antarctica to scout for the strategic mineral iridium. After their plane crash-lands, Keltyn and her Canadian crew-mates discover that the land is now home to the Onwei, a tribe of nomadic cattle-herders. She befriends two teens: orphan would-be gaucho Joaquin Beltran, and horsewoman Luz Hogarth, who is likewise searching for the elusive iris stone, from which her mother fashions the fine jewelry that supports them.Despite censure from tribal leaders and Keltyn’s crew, she and Luz are soon scrambling up the slopes of the nearby Erebus volcano, where they find a lode of high-grade iridium. Mortal danger awaits, and not just from the volcano. Keltyn learns that her ruthless sponsor, Sir Oscar Bailey, plans to use her iridium discoveries to enable the transport of Canadian farmers to colonize Antarctica. Keltyn’s loyalties are already in flux. Soon she is forced into an ill-conceived gamble that spirals into free-fall. A scheming bitter shaman and a vindictive new gaucho leader fan suspicions against the “Sky-Bornes.” Luz and Joaquin are the only ones who can help, but each must first survive their own ordeals.