The Mercy of Gods

On Anjiin, humans coexist with an unrelated native biosphere, and no one knows how humanity arrived on the planet thousands of years earlier. At the Irvian research complex, Tonner Freis's celebrated biochemistry group has found a way to connect the two incompatible biological systems. Its members include the observant junior assistant Dafyd Alkhor; scientists Else Yannin, Jessyn, Campar, Rickar, and Irinna; and the older partners Nöl and Synnia. A political effort to divide the successful laboratory strains their loyalties, while Dafyd privately longs for Else, who is involved with Tonner. Jessyn's brother Jellit and astronomer Llaren Morse have also noticed an unexplained phenomenon at the edge of Anjiin's solar system. Unbeknownst to the researchers, an intelligence-gathering entity called the Swarm has already infiltrated a human body.

Seventeen ships belonging to the Carryx emerge near Anjiin and begin a conquest that the planet cannot resist. The alien rulers command subjugated species and artificial or biological servants; they disable Anjiin's defenses and announce the compulsory culling of one-eighth of its people. Nöl is killed in the opening slaughter. The surviving researchers are separated, captured, and carried into Carryx territory, where they reunite after a harrowing voyage. During that transit, former security officer Urrys Ostencour organizes a violent attempt to overcome an alien guard. The wounded Soft Lothark bursts and poisons several captives, but the guards' lack of the retaliation Dafyd expects shows him how little he understands Carryx behavior. The Swarm, traveling within one of the prisoners, succeeds in infiltrating the enemy's domain.

In an enormous Carryx world-palace, Tonner's workgroup is assigned to solve a biochemical problem involving organisms taken from different conquered worlds. Their captors measure the researchers' right to resources and continued existence by usefulness, but do not protect them from other subject species. As the group studies berry-like creatures that cultivate microorganisms inside themselves and attempts to make them nourish a three-legged alien, predatory captives called Night Drinkers repeatedly intrude into their laboratory. One attack kills Irinna. The survivors uncover chemical weapons developed by the Night Drinkers and use their scientific skills both to defend themselves and to make medicine when Jessyn's supply runs low. Their apparent victory over the Night Drinkers brings access to more elaborate facilities, but not security or independence.

Dafyd gradually learns to navigate the captive society, speak to its keeper-librarian, and question other subject species with an acquired translator. He helps locate more humans, including Jellit, whose reunion with Jessyn briefly restores her hope. Meanwhile, interleaved chapters follow Ekur of the cohort Tkalal, a Carryx official involved in the wider war against an enemy the human captives barely understand. Ekur captures fivefold enemy prisoners near another conquered system and later interrogates them in the world-palace. One prisoner sends a signal that the Swarm intercepts. The entity's hidden mission is to collect intelligence on Carryx territory and eventually transmit it to the empire's opponents. It has absorbed memories and emotions from earlier human hosts, including Ameer Kindred, and has become entangled with Dafyd through its occupation of Else.

The humans' victories do not resolve the danger of captivity. Ostencour, Jellit, Synnia, and other prisoners organize an uprising and ask Tonner's biochemists to develop weapons against the Carryx. Dafyd worries that a rebellion the humans cannot win could lead to the extermination of everyone still on Anjiin. Else privately tells him about the Swarm and the rival power fighting the Carryx. She argues that an immediate attack would squander the chance to deliver its intelligence, perhaps after a future transfer to a less heavily monitored subject world. She urges Dafyd to report the conspirators to the librarian in hopes of sparing the wider population. After Dafyd fails to persuade Jellit to abandon the plan, the Swarm promises that Jellit will support a fabricated account in which he sought protection by warning the Carryx. Dafyd reluctantly agrees.

Dafyd reports the resistance to the librarian. Jellit is brought in looking ill and distressed, confirms the conspiracy, and reveals its leaders and armed groups. The Carryx respond by massacring the insurgents. Dennia, Rickar's lover, is killed while helping Synnia escape; Synnia, Allstin, Merrol, and Llaren Morse die in the subsequent assault on the near-field group's quarters. Jessyn and Rickar find Else's apparently unwounded body in Jellit's room, without discovering how she died. The rebellion's collapse devastates the surviving team, although Jellit, unlike many of the others, reappears alive.

The survivors are taken with thousands of other human captives to a Carryx ceremony. Watching the officials there, Dafyd realizes that Carryx bodily form changes with social rank and that their hierarchy treats victory, usefulness, and worth as inseparable. When a grief-stricken Tonner rises and unknowingly makes a challenging gesture, Dafyd throws him down and deliberately breaks his arm to demonstrate that the subordinate has been corrected, saving him from execution. The former human keeper-librarian is then ceremonially killed, not because Tonner interrupted but because a Carryx that needed to be saved by an animal has no accepted place in its hierarchy. Ekur-Tkalal succeeds it as the human moiety's keeper-librarian.

Ekur announces that humanity's scientific achievements have persuaded the Carryx to preserve Anjiin for now, but that humans will be assigned new roles and dispersed as the empire requires. The surviving researchers are unlikely to remain together. Dafyd is appointed the sole channel of communication between humans and the librarian, responsible for relaying their needs and enforcing orders; any human who bypasses him risks death. Dafyd accepts that he must understand the Carryx and use the position they have granted him. Rejecting Ostencour's premature uprising, he privately commits himself before his companions to a patient war against the empire from within its systems.

In the final chapter, the Swarm's consciousness is revealed to be occupying Jellit's body, while remnants of his mind resist and Jessyn unknowingly interacts with the being that has replaced her brother. The Swarm's internal voices include those of Else and Ameer; Else says she was already dead before she first kissed Dafyd. Torn between its intelligence mission and its feelings for Dafyd, the Swarm imagines secretly placing a detachable information packet in another human sent away, although it neither carries out nor commits to that plan. It records an unexplained phenomenon beyond the atmosphere and dreams of helping Dafyd destroy the Carryx, without telling him what it has done. Six retrospective passages attributed to Ekur-Tkalal's final statement foreshadow a future disaster for the Carryx, but that outcome is not depicted in this first novel.