Nica would rather be honing her Guardian skills than taking on the responsibilities of leading the nuptial pod for Rissa, her older sister, who will be bonding with Jonnat. Nica’s father is the Head Guardian of the Olomi, an amphibian people who reside in the Deep, and she’s long dreamed of following in his wake. But when an alien force suddenly arrives, it shatters the world as she knows it. Rissa goes missing, along with many other Olomi. Jonnat and Nica team up to retrieve Rissa, but Nica is captured by TAL, one of the invading landwalkers. Enslaved with other abducted Olomi in harsh, dry conditions, Nica despairs as she’s forced to serve the cruel landwalkers, whose goal is the exploitative agricultural terraformation of the Olomi’s world. Horrifyingly, Nica and her friend Pescha have been selected for invasive medical tests. Nica manages to make friends and to find allies who will sacrifice everything for a chance to return to the Deep. Hansen captures both the beauty of water and the brutality of slavery. The environmentally harmonious lives of the Olomi sharply contrast with those of the enslavers, who seek to bend the planet to their will; the parallels with trans-Atlantic chattel slavery are abundantly clear (and reinforced by Olomi vocabulary that echoes Yoruba words). The ending sets up for a sequel that readers will anticipate. Characters are fantasy diverse in appearance.