The Strength of the Few

The novel begins just after the Labyrinth, when Vis follows Caeror into Obiteum and learns the scale of what has happened. The ancient Rending split existence into Res, Obiteum, and Luceum, and Vis's passage through the Gate created parallel versions of him in those worlds. Caeror explains that the Cataclysms are not natural disasters but recurring culls carried out by the Concurrence, and that another may be imminent. From that point on, the book follows Vis across the three sundered worlds at once. In Res, he is pulled deeper into Caten's politics; in Obiteum, he is trained for a mission against Ka in Duat; and in Luceum, he is forced into the wars of kings and druids under new names and identities.

In Res, Vis returns from the Iudicium grieving Callidus and furious at the systems around him. He joins Governance under Magnus Tertius Ericius, confronts Ulciscor as an equal, and arrives at the Aurora Columnae only for the ritual to fail. Lanistia suddenly attacks him under the control of an outside force, and her imprisonment becomes one of Vis's central wounds. Emissa later explains that she once believed Vis had become one of the undead iunctii and warns him that a blood test before Placement will expose whatever changed in him beyond the Labyrinth. With Eidhin's help, Vis survives the test, enters Governance, and begins to understand a new power called Adoption, which lets him sense and seize Will already imbued into objects. That hidden ability helps him excel in Placement and the Circus Sciacca trials, where he secretly manipulates imbued objects and wins a brutal chariot race with Aequa. Even so, politics keep him from the expected promotion, and he turns increasingly toward investigation rather than office.

As Res destabilizes, Vis also peels back the truth behind Solivagus and the Iudicium. Lanistia, Relucia, Emissa, and Veridius each reveal fragments: Lanistia was compelled by a voice tied to the ancient machinery beneath Solivagus, Emissa was once prepared by Veridius for a role in stopping a new Cataclysm, and Veridius believes Vis may now be Synchronous, existing across worlds in the one way the Rending was meant to prevent. Vis returns to Solivagus with Aequa and Eidhin, finds the hidden chamber full of corpse-bound iunctii, and activates a device that warns that Obiteum is lost and Synchronous is death. Veridius finally admits that Lanistia and Marcus were broken by the same device while trying to bypass the Labyrinth's defenses. Soon after, the festival of Pletuna pushes Caten into open crisis. Ostius transports Vis between worlds, uses him to expose and force confessions from senators tied to the naumachia, Solivagus, and the destruction of Suus, and then turns the aftermath into a massacre that triggers civil war. Vis becomes the masked vigilante Carnifex, learns from Baine Breac that Princeps Redivius is about to attack Caten, and is preparing to rescue Lanistia when Tertius Decimus murders Aequa and cripples him. Even so, Vis forces his way into South Caten Prison, frees Lanistia and Ulciscor, leaves Relucia to die on a Sapper after extracting names and truths from her, and then goes out to meet Redivius's assault. At the docks he finally reveals to Eidhin that he is really Diago, son of Cristoval of Suus, and persuades him not to die for Redivius's cause. Together they seek Ka, who claims the Cataclysms are a horrific defense against the Concurrence rather than simple destruction. Desperate to end the war, Vis accepts Ka's guidance to a hidden chamber beneath the Necropolis and triggers a Cascade that awakens nearly eighty thousand preserved dead into an army under his command. The terrible cost of that decision becomes immediate when he discovers that the risen include his own mother and sister.

In Obiteum, Caeror brings Vis to Qabr and begins turning revelation into purpose. Vis learns that Will in this world can sustain the dead as iunctii, that Gleaners are blade-limbed servants of Ka, and that Vitaeria are actively preserving him in the poisoned desert. Caeror proves that even the dead can be turned into traps by the Concurrence, and he explains that Ka's existence across worlds may be what sustains the next Cataclysm. To stop him, Vis must learn to command iunctii as Ka does. Training with the volunteer Tash horrifies him, because he discovers through a Harmonic link that the Instruction Blade leaves its victim conscious, terrified, and helpless. Caeror also leads him toward an ancient golden door whose hum triggers Vis's trauma from the naumachia, but before he can master that fear Qabr is devastated by a Gleaner raid. With no other route into Duat, Vis controls a single Gleaner, Duodecim, has it spear him, and lets himself be carried into Ka's city disguised as a corpse.

Inside Duat, Vis rescues Ahmose rather than sacrifice him, loses Duodecim, and survives only by hiding among the western dead. He eventually reaches Netiqret, a mesektet assassin, and through her discovers the hidden systems under Duat: the Nomarch that controls the Overseers, the infernal waterworks that purify drinking water through mutilated bodies, and the private grief driving Netiqret's rebellion. Netiqret's damaged daughter Kiya, still linked to the Nomarch, gives Vis crucial information about Ka's defenses. Vis infiltrates Ka's Sanctum as a dancer, reaches the Nomarch, and learns that the bridge over the Infernis is the city's true artery and that the Gleaners guarding Ka will only move for an existential emergency. That attempt collapses when Ahmose is exposed and publicly denounces Ka before killing himself in the Infernis to keep Ka from taking him back. Vis escapes through acid channels, returns to ruined Qabr, discovers that its hidden life also depended on a grotesque water-harvesting system, and forces himself through the mutalis chamber he once feared. There he claims the blood-activated crook and flail, weapons powerful enough to destroy Duat's obsidian. Armed at last, he returns to Duat, destroys the great bridge, draws the Gleaners out of position, and is saved by Netiqret and Kiya after nearly dying in the poison again. Kiya then uses her remaining link to the Nomarch to buy him one hidden hour. Vis crosses the emptied Sanctum, finds Ka not on a throne but lying catatonic on a powered stone table, and chooses to stab him through the heart before the Gleaners can stop him.

In Luceum, the parallel Vis wakes maimed on a boat and is nearly executed before the draoi Cian secretly frees him. Cian is soon killed, and Vis survives the aftermath only because Gráinne and her family hide him on their farm, where he lives for a time as Deaglán and discovers a rare peace outside the Hierarchy. That refuge ends when Lir traces Cian's staff to him and brings him to Caer Áras. There Deaglán avoids execution by swearing himself to King Rónán, survives Gallchobhar's hostility, and is sent to Loch Traenala, where Tara and the other young fighters force him to rebuild himself around the loss of his arm. He gradually becomes part of their warband and begins to manifest the nasceann, a black-eyed state of battle clarity tied to the druids and the old ways. Along the way he learns that the Grove has been corrupted by Ruarc's faction and is backing Fiachra in a coming succession war.

Deaglán's path then turns into a confrontation with his own past. He follows a strange pulse and meets his supposedly dead father, Cristoval of Suus, who reveals that Military revived him with a Vitaerium after his execution. Cristoval explains that Suus was destroyed because he uncovered evidence that the Cataclysms recur, that the Republic already knew, and that Suus had also found a weapon the Hierarchy feared. He later tells Deaglán that the world was split into three realms and that this version of him now lives in Luceum because of the Labyrinth. Lir next takes Deaglán to the submerged city of Fornax, where an Aurora Columnae identifies him as Synchronous and turns its silver guardians on him. Deaglán survives only by discovering that he can manipulate their Will and by escaping with a silver arm torn from one sentinel. Gallchobhar murders Lir, delivers Deaglán to Fiachra's siege of Caer Áras, and prepares him for sacrifice. Tara tries to rescue him and nearly matches Gallchobhar in single combat, but Rónán must surrender himself to save her. Gallchobhar then publicly beheads Rónán and drowns Deaglán. Under the water, Cristoval gives his Vitaerium medallion to his son and dies in his place. Guided afterward by Lir's lingering presence, Deaglán rises from the lake with his silver arm working, appears to both armies like a sign from the gods, kills Gallchobhar in front of them, and breaks Fiachra's assault. When he wakes in Caer Áras, now celebrated as Silverhand, he buries his father with Tara and the others and finally accepts that these people are his own. Then the defeated Ruarc asks to speak and reveals that he is really Caeror, Ulciscor's brother, another traveler from beyond Luceum, and a man who believes one of Vis's other selves has made a disastrous mistake.