The novel begins on the planet Anjiin, where humans live alongside a native ecosystem with a different biochemical basis. Humans are believed to have arrived on Anjiin thousands of years ago, though their exact origins are unknown. Dafyd Alkhor is a low-level research assistant in Tonner Freis's celebrated workgroup, including Else Yannin, Jessyn Kaul, Campar, Rickar Daumatin, and Irinna. Freis's group has risen to preeminence in its succeeding in "
reconciling" the two different biochemical "
trees of life" native to Anjiin—understanding and thus being able to alter their metabolisms, such that they can enter into an
ecological relationship. Anjiin is suddenly invaded by a vastly technologically superior alien species called the Carryx and their subservient species. After killing one-eighth of the population, the Carryx abduct many of the planet's social and scientific elite, including Dafyd's group. The captives are taken aboard Carryx ships and transported to a distant star system where the administrative center of the Carryx empire is located in a massive world-city (known as
world-palace among the Carryx). In one of its
ziggurats, Dafyd's group is assigned to a research project by their Carryx overseer (
keeper-librarian), referred by humans simply as the librarian, who reminds them that humanity's survival depends on their usefulness to the Carryx. The task involves making one alien organism (referred to as "berries") nutritionally compatible with another (called "not-turtles"). As the group struggles to adapt to captivity, they face various challenges. They must defend themselves against attacks from another captive species called Night Drinkers. Jessyn battles her
mental health issues without her medication. Relationships within the group become strained, particularly between Tonner, Else, and Dafyd. Meanwhile, a resistance movement forms among the human captives, led by Urrys Ostencour, who plan to create bioweapons to use against the Carryx. Some members of Tonner's group, like Synnia, become involved. Dafyd learns from Else that she is host to an entity called the Swarm – a spy sent by the Carryx's enemies in an ongoing interstellar war. Else convinces Dafyd to betray the resistance to the Carryx to protect their long-term chances of survival. Torn between loyalty to his fellow humans and fear of the consequences, Dafyd ultimately decides to inform the Carryx librarian about the rebellion plot. This leads to a violent purge, resulting in the deaths of many humans, including Synnia and Else, who dies after the Swarm exits her body. The Carryx execute one of their own, the librarian, for being "
saved by an animal". In the aftermath, a new Carryx
keeper-librarian of the humans named Ekur-Tkalal is appointed, who informs the survivors that they have proven useful to the Carryx and will be assigned new duties. Dafyd is made the sole intermediary between humans and the Carryx. The group is likely to be separated, but Dafyd vows to find a way to defeat the Carryx in the long term. Now in Jellit's body, the Swarm contemplates its mission to transmit intelligence back to the Carryx's enemies, but finds itself conflicted due to its growing emotions and attachment to Dafyd. == Species ==