The novel is set on a frozen alien world called Not-Hoth, where 15 human women, abducted from Earth and abandoned by alien slavers, have been taken in by the sa-khui, a tribe of large, blue-skinned, horned aliens who live as hunter-gatherers in icy caves. Each human received a khui, a symbiotic organism that sustains its host in the lethal atmosphere and pairs them with a genetically compatible mate through "resonance," a chest vibration that grows unbearable until the pair mates and conceives. Over the past year and a half, nearly every human woman has resonated to a sa-khui male and started a family. Only Josie remains unmated; her IUD, an implanted birth control device, has prevented her khui from triggering resonance.
Josie, the narrator and protagonist, watches Tiffany, the last other single human woman, pair off with her resonance mate, Salukh. Having grown up cycling through foster homes with no permanent family, Josie aches for a mate, children, and belonging. She considers Haeden, a surly hunter, her least favorite person in the tribe.
That evening, Josie discovers that her khui has silently expelled her IUD. Elated, she circulates among the unmated males, but her chest remains silent. Then, near the fire, resonance erupts. She turns to find Haeden behind her, his own chest thrumming in answer. Josie is devastated: Her khui has chosen the one person she believes despises her.
Haeden pulls her to his cave. Josie declares she will not sleep with him, and Haeden agrees not to touch her until she asks. The narrative shifts to his perspective, revealing he does not hate Josie. He has felt drawn to her since carrying her from the crash site but pushed her away out of terror. He once resonated to a woman named Zalah, and the bond ended in tragedy; his original khui burned out during a devastating illness, and the replacement he received is how he can resonate a second time.
Josie avoids Haeden for weeks. He prepares a private cave for them and throws himself into relentless hunting, but both deteriorate physically. When Aehako, a friendly hunter, confronts Haeden about his condition, Haeden finds Josie gaunt and sluggish in a storage cave. Unable to bear her suffering, he offers to take her to the elders' cave, a crashed ancestral sa-khui spaceship, so she can use its surgery machine to remove her khui and end the resonance.
At the elders' cave, Harlow, a mechanically gifted human who lives there with her mate Rukh, delivers crushing news: The surgery machine is broken beyond quick repair. Josie retreats into the ship to think, reflecting on her history of sexual abuse in foster homes, assault by aliens during the kidnapping, and painful relationships. She dreads a loveless pairing but resolves to give in, reasoning she has no other options.
Before telling Haeden her decision, Josie asks about his past. He shares the full story: Zalah was much older and already had a pleasure mate. When the young Haeden resonated to her, she refused him. Before the bond could be fulfilled, a khui-sickness, a lethal illness affecting those with the symbiont, swept the tribe, killing Zalah, Haeden's parents, and many others. Haeden is the sole survivor. His losses shift Josie's understanding of him.
Josie tells Haeden she is ready. In a private room, he touches her for the first time but, overwhelmed, ejaculates prematurely. Humiliated, he snaps at her. Interpreting his harshness as contempt, Josie storms out, declaring she cannot bring a baby into such a relationship.
While Haeden remains trapped in the room, Josie steals supplies and sets off alone toward the coast. Haeden escapes with Harlow's help and follows at a distance, watching over her without revealing his presence. Over several days, Josie finds hunter caves for shelter and rations food with surprising resourcefulness.
At the coast, Josie spots a crashed ship at the base of distant mountains. She deduces it is the vessel that Kira, another human woman, crashed months earlier while escaping alien slavers. Inside the cargo bay, she discovers stasis tubes with two green lights indicating living occupants, likely kidnapped human women. The discovery forces her hand: These women need khui symbionts to survive, obtainable only by hunting a massive sa-kohtsk creature. Josie must return to the tribe.
Emerging from the ship, she sees Haeden fighting a pack of metlaks, tall and aggressive predators, on a distant hill. She ignites a scavenged alien blanket against the ship's emergency light, badly burning her hands, and charges the creatures. They scatter. Haeden pulls her into a crushing embrace, the first time he has held her.
Haeden treats her burns with chewed liidi root, a numbing plant, and tends to her every need while her hands heal. Josie tells him about her childhood in foster care, and Haeden reacts with explosive rage. Josie realizes no one has ever been angry on her behalf. He explains that his hostility was never hatred but fear of losing her. Their shared vulnerability forges a new bond.
Once her hands heal, Josie asks to detour south, wanting private time. They grow closer, and Josie initiates physical intimacy on her own terms, starting with kissing, which Haeden has never done. The mutual pleasure, freely given without the pressure of completing resonance, transforms them from adversaries to partners.
Their journey inland turns dangerous when a sky-claw, an enormous predatory bird, swoops down and snatches Josie into its mouth. Haeden, believing her dead, presses his knife to his own chest. The creature crashes: Josie has been stabbing it from inside. Haeden slits its throat and pulls her out alive. He carries her to a hunter cave, and when she wakes, he declares she has always been his and he will always come for her.
After recovering, Josie consummates the resonance from genuine desire, not resignation. Haeden's tenderness and vulnerability dissolve her last defenses. She tells him she loves him. He does not say the words but tells her that when the sky-claw took her, he put a blade to his heart, something he never did for Zalah.
They mate repeatedly as resonance demands, then journey home with Haeden carrying Josie strapped to his chest for protection. At the tribal caves, they report the crashed ship and the women in stasis to Vektal, the chief. A rescue party departs, including Haeden, unmated hunters, and Kira, who insists on confronting her guilt over the crash. Josie stays behind. Three weeks later, the party returns with one new woman, Maddie. Her sister Lilah is missing, apparently gone with one of the hunters. Haeden carries Josie to their cave, where she tells him she is pregnant. For the first time, he says he loves her.
A bonus novella follows the couple one month later as they explore their sexuality together. After a miscommunication involving dirty talk, they consult friends, discuss boundaries, agree on a safe word, and experiment with role-play. When morning sickness triggers Haeden's panic, the tribal healer, Maylak, confirms Josie and the baby are healthy. The novella closes with Josie expressing deep contentment: She finally has the loving mate, growing family, and sense of belonging she longed for her entire life.