The third installment in the series that began with
The Blacktongue Thief and continued with
The Daughters' War, the novel follows Kinch Na Shannack, a Galtish thief, and his companion Galva dom Braga, an Ispanthian knight, as they flee west across the Thrall Mountains with a stolen Book of the Full Shadow. Kinch possesses the Cipher, a rare birth-gift allowing him to read any language, including the Book's Murder Alphabet, a lethal script that kills unprotected readers. One of twelve sentient tomes belonging to the Takers Guild, the criminal organization Kinch has betrayed, the Book holds secrets that could expose the Guild's grip on Manreach, the known human world.
At a remote village, Kinch buys provisions, hires a Wostran guide named Worrig, and traps the Book in an iron bear trap to suppress its magic. When Worrig's estranged wife Ylda ambushes them with brigands, Galva releases Dalgatha, her stag-sized war corvid stored in a magical tattoo on her chest, and they rout the attackers. Returning, Kinch finds the Book has animated Worrig's corpse with inky tendrils, revealing its power to possess the dead. They shelter in the brigands' cave, where Kinch kills the captive brigands by exposing them to the Murder Alphabet.
Deeper in the Thralls, predatory owl-things attack, and in the chaos the donkey and most provisions are lost. Kinch survives a fall into a crevasse thanks to his Catfall ring, which cushions falls, and threatens to burn the Book, forcing it to cooperate. The Book then sabotages their remaining supplies, leaving them destitute.
They retreat to the cave, where Galva develops a lung infection. Kinch reads the Book while nursing her, and it attacks through dreams, manifesting as a woman named Filaine who tries to trap his soul. Norrigal, Kinch's witch lover, intervenes in the dream, provides medicine for Galva, and sends a map to a temple of the God of Threes, though she cannot reveal what the god demands. During Galva's weeks-long recovery, Kinch discovers that Filaine's body was destroyed by the Guild to animate the Book, making her both its prisoner and one of its monstrous manifestations. He considers destroying the Book to free her but cannot abandon its potential secrets.
When Galva recovers, they trek to the temple and find the God of Threes: a living thirty-foot statue with three heads and six arms. It demands they accept unknown terms; as the temple begins to entomb them, Galva agrees. The god triplicates both of them, creating three versions of each with all gear and copies of the Book. It destroys one pair in fire and hurls a second back east. The remaining Kinch throws his Book into the god's fire rather than let the god examine the Murder Alphabet. As it burns, he perceives a gasp of release, as though Filaine's soul is freed. The god flings the last pair into the Giantlands, bookless.
They awaken in a warm, unfamiliar land. Nearly dying of thirst on the arid plains, they eat hallucinogenic berries, are saved by rain, and are captured by Wostran slavers. Galva refuses to join the company, so both are marked for sale. True giants later ambush the caravan, but an Erydoni cloud-ship, a flying vessel lifted by sathium gas, drops thunderdust, a devastating explosive, destroying the attackers. The slavers continue to Tinthrax, the northernmost outpost of the Kingdom of Erydon, a half-giant civilization that wields volcanic blackglass weapons, flies cloud-ships, and worships the fire god Thumos. At a slave auction, the gladiator-owner Verna Zan Zan buys Kinch and Galva. Galva declares before the crowd that she will fight but never be a whore.
At Verna's gladiator school, Kinch and Galva fight and kill a giant together at the Blood Chalice arena. Kinch's antics catch the eye of Princess Renata, the king's cruel eight-year-old daughter, and King Agraias purchases both: Galva for his elite gladiator stable, Kinch to replace the dying court fool. In the capital, they are separated.
Kinch befriends his predecessor Hasp, an aging Galtish fool who teaches him the craft. Hasp's quiet kindness extends even to Pulhu, an enslaved giant called a geigon who operates the palace elevator in chains; when Renata wounds Pulhu, Hasp brings him blueberries, and the blind giant weeps. Kinch also meets Quiggles Silversides, a cuttlefish from the underground Sunless Sea who communicates through luminous writing. At night, Kinch maps the palace through hidden tunnels and forges a skeleton key with help from Zherit-Nassk, a cyclops blacksmith. When Hasp dies, Kinch grieves deeply. Meanwhile, Galva becomes the arena's most famous fighter, earning the name "the Tiger's Sister" after she refuses to fight a tiger named Jubel and rubs its belly instead.
When a goblin embassy from the Horde, the organized goblin power, arrives seeking an alliance with the Erydoni, the stakes become clear: If the half-giants share thunderdust and cloud-ships with the goblins, Manreach faces destruction. Extra games entertain the embassy. Galva fights Apia "the Bee," an Istrean fighter wielding a slakesword, a specialized bladed weapon, along with a goblin and a bear. Jubel is killed. Galva defeats Apia but takes a deep belly wound and signs to Kinch in hand-cant: "You must kill them." Unable to penetrate the embassy's defenses alone, and learning that Galva survived, Kinch realizes he can faithfully reproduce any script he has read, including the Murder Alphabet.
The night before the Apocalypse ceremony, a public spectacle in which godwords on clay tablets are ignited and raised to simulate divine authorship, Kinch writes the Murder Alphabet between the godwords. At the ceremony, he grabs Renata's face and pokes her eyes to prevent her from reading; the queen shields herself and her daughter. Thousands of literate Erydoni die upon reading the tablet. King Agraias collapses. Thumos erupts.
Slaves revolt across the city. Pulhu breaks free and, hearing the jingle of Hasp's bell in Renata's hair, crushes the princess hiding in a trunk. Kinch frees Galva from the gladiatorial facility under volcanic bombardment. On the rooftop, they find the goblin embassy seizing a cloud-ship. In the fight, Dalgatha is killed, and Kinch, stabbing through the last goblin with a blackglass sword, accidentally drives the blade into Galva, compounding her belly wound.
Galva dies peacefully on the drifting cloud-ship, believing she goes to meet her goddess. Kinch describes through a farglass, a type of spyglass, how the freed Pulhu rescues Quiggles Silversides from the garden pools ahead of the advancing lava. Alone, Kinch throws three barrels of thunderdust overboard, refusing to let such weapons reach Manreach. A storm carries the ship north; Norrigal sends warmth through a dream, and lightning frees Bully Boy, Kinch's blind tabby cat, from a magical tattoo on his arm. The cloud-ship crashes near the brigands' cave from the story's beginning.
Inside, Kinch finds the body of his other self, the version the God of Threes sent back east, dead from a head wound after fighting Guild assassins. A letter in the dead Kinch's failing handwriting reveals instructions for unlocking the Book's deeper secrets and a pivotal revelation about a conspiracy from the earlier novels. The surviving other Galva emerges, thin and scarred, still carrying the third copy of the Book. They arrange the bodies to fake their deaths, burn the cloud-ship to prevent its technology from being replicated, and set out east with the Book on a sled. As they walk, Galva begins telling Kinch about her experiences in the Goblin War, a story she told the dead Kinch but that this Kinch has never heard, opening the next phase of their journey.