The second installment in Shannon Chakraborty's Amina al-Sirafi adventure series opens with the unnamed scribe-narrator warning that this tale nearly destroyed a friendship he believed unbreakable. To establish the crew's bond, he recounts an earlier adventure: retrieving the Mortar of Mithridates from beneath the ruins of the ancient Indian port city of Muziris. The mortar is the Second Transgression, one of five dangerous magical artifacts Amina is tasked with recovering as part of a deal she struck with a council of peris, or air elementals. Her crew comprises Dalila, a poison expert; Tinbu, the shipwright and first mate; and Majed, the navigator. They solve deadly traps, pry the cursed mortar from a dead physician's hands, and barely escape a catastrophic flood.
Back in Oman, Amina's family pressures her to move from their isolated hillside fort to the nearby town of Salalah. Her mother and brother Mustafa argue that the children are suffocating, especially Amina's 11-year-old daughter, Marjana, whose father is Raksh, a chaos spirit Amina drunkenly married years ago. Amina resists, fearing exposure could reveal Marjana's supernatural heritage. She also discovers Dalila has secretly scraped residue from the mortar for her own experiments, defying the peris' prohibition against using the Transgressions.
That night, the peri Khayzur arrives on Amina's roof. He detects chaos-spirit magic, which is actually Marjana's latent abilities, but Amina deflects his suspicions. Khayzur explains that Raksh rescued a man who escaped the island prison of a sorceress named Lab, and the escapee is now luring fortune seekers toward Lab's domain with tales of treasure. The peris fear the seekers will discover the Third Transgression: an ancient spindle capable of rewriting memories and altering fate that feeds on vengeance. Amina accepts the quest, knowing refusal would invite scrutiny of her family. After Khayzur departs, Marjana reveals she has always heard whispers and seen shadows no one else can. Amina tells her only that her father's people had "an affinity for magic."
Amina and Dalila clash over strategy: Amina wants to consult Jamal al-Hilli, a young occult scholar in Baghdad, while Dalila wants to hunt Raksh directly. Dalila vanishes before they resolve the dispute, stealing Amina's meteor blade, a mystical dagger, and setting off alone. Amina departs aboard her ship, the Marawati, on bitter terms with her family. During the voyage, Marjana is discovered as a stowaway, and Amina decides to leave her in Jamal's care in Baghdad. There, Jamal shares research linking the spindle to massacres and madness, and recounts a tale from medieval Arabic literature describing Queen Lab as a sorceress who transforms shipwrecked men into livestock.
Weeks pass until a parcel arrives containing Dalila's bloodied headdress and a note from Sheikh Sasan, leader of the Banu Sasan, the criminal guild Dalila defected from decades ago. Using forged letters, Amina lures old enemies to Sarilaglag, a hidden floating criminal town in the Persian Gulf, to create chaos while she rescues Dalila. She confronts Raksh, who engineered the situation to draw Amina out. When rival pirates and arsonists arrive, Raksh amplifies the chaos magically, and Amina frees Dalila during the brawl. Sarilaglag burns as they escape.
The Marawati sails south toward Lab's island, but the stars shift nightly, trapping the crew in uncharted waters. Amina experiences dizziness, blisters, and headaches. A catastrophic storm kills six crew members and wrecks the ship on a strange island. Locals from Khatti Ugal, a kingdom ruled by queens descended from Lab, bring aid and explain that no one has ever sailed away. The crew travels to the White City, where eerily placid inhabitants wear brilliantly dyed cloaks. Queen Lab proposes a deal: She will fund repairs in exchange for Amina and Dalila remaining at the palace, with some crew members staying permanently. Amina accepts while planning to steal the spindle.
Palace life proves treacherous. Amina's visions intensify, showing ruins beneath the city's beauty, while Dalila spends increasing time with the queen. Exploring underground tunnels, Amina discovers catacombs of thousands of skulls and a textile workshop where silent workers tend a towering, living tapestry whose color patterns match the dyed cloaks of specific citizens. Lab tests Amina by sending her unarmed against griffins, which she kills with supernatural strength. When captured bandits reveal Amina's pirate identity, she confesses to Lab and negotiates a fragile new arrangement.
Dalila reveals a devastating secret: Sheikh Sasan poisoned the meteor blade before returning it through Raksh, and Amina has been slowly dying since Sarilaglag. There is no cure, and Dalila concealed the truth while secretly treating her. Their friendship fractures. Amina also discovers that Lab's magic bends the forest back on itself, trapping her and Dalila in the city, cut off from the crew.
Through interludes told in second person, the novel reveals Lab's origin: a grieving mother whose village was destroyed by raiders merged with a forgotten goddess of fates, channeling rage through a blood-soaked spindle. Over millennia, the entity possessed successive hosts and consumed the magic of daevas (fire elementals) and marid (water elementals) before the marid and peris trapped her on this island. She built Khatti Ugal from castaways, spinning their souls into thread and weaving them into cloaks that resurrect the dead as obedient, eternal subjects.
Amina discovers Dalila spinning thread with Lab, the spindle between them. Dalila reveals she claimed to be the poisoned one and offered to serve Lab in exchange for learning to create a magical healing belt for Amina. Dalila intended to remain in Khatti Ugal permanently so Amina could live, but Amina refuses the belt, unwilling to use magic woven from enslaved souls. Meanwhile, Lab has replaced Raksh with a construct spun from his memories. When the construct attacks Amina, she destroys it.
Amina devises desperate sabotage, cutting her hair and smuggling strands into the raw wool Lab's workers spin. The enslaved workers deliberately distribute the hair throughout the tapestry. The enchantments unravel: Palace wings crumble, and Khatti Ugalans who remove their cloaks crumble to dust, the shrouds revealed as soul-binding prisons.
Lab confronts Amina and Dalila. Dalila assassinates Lab, but the dying queen shoves the spindle into Dalila's hands, and Lab's consciousness floods her mind. Dalila fights long enough to shout "Get Raksh!" before Lab seizes her body. Amina races to the dungeons, where the real Raksh has been flayed open. She stitches him together and rouses him by promising, "I will let you make me a legend." At the harbor, Lab, possessing Dalila's body, lures Majed ashore and slashes his throat. Amina saves him with Dalila's healing belt. Raksh unravels the spindle's magic while Majed seizes the spindle and hurls it to Amina, who snaps it over her thigh.
Khatti Ugal collapses, its woven reality dissolving. The entity that was Lab crumbles into dead leaves in Dalila's arms. Of the kingdom's thousands, fewer than 50 living souls remain. Eight months have passed for the crew while Amina experienced only weeks inside the enchanted city. Dalila, freed from possession, buries the shroud of Lab's son Pares and continues developing a cure for Amina's poisoning. Amina summons Khayzur, hands over the broken spindle, and terminates their deal, accusing the peris of using her as their "permissible" assassin. Khayzur warns that the council considers Amina herself a Transgression.
During the two-month voyage home, Amina and Dalila rebuild their friendship, and Dalila shares her real name and origins. When fishermen appear near Muscat, Tinbu delivers devastating news: The journey that felt like months has spanned 10 years. The novel ends with Amina a day's sail from home, facing the reality that her daughter is now a young woman and her family has lived a decade without her.