The servants at Duke Keramsov's orphanage call the two youngest children malenchki - little ghosts - because they haunt the estate like giggling phantoms, hiding in cupboards and stealing summer peaches. Alina Starkov and Mal Oretsev arrived within weeks of each other, orphans of the border wars. Hiding in a kitchen cupboard, Alina overhears Ana Kuya, the housekeeper, call her ugly, pale and sour. Mal whispers that he does not think she is ugly, and in the shadows she smiles.
They grow up together through summers of chores and secret swims in the creek, winters hiding from older children in disused rooms, dreaming of a dairy farm with white cows. One winter day, three Grisha Examiners arrive in a troika pulled by black horses, wearing kefta of crimson, blue and purple. The children spy from a balcony as Ana Kuya receives the visitors. Mal blurts out that they are witches, earning a sharp rebuke from the woman in red, who insists they are practitioners of the Small Science. The young man in purple spots the hiding children, and Ana Kuya summons them downstairs. The Examiners explain they have come to test whether either child is Grisha, promising the finest clothes and food. But as the adults talk, unnoticed, Alina clasps Mal's hand - and both children share a look of fierce, unyielding determination not to be separated. The Duke would have recognised that look: the defiance of people defending what they love with nothing but bare hands.
Alina's regiment marches toward the Shadow Fold for a crossing to West Ravka. Mal tries to ease her fears, but is distracted by a beautiful Grisha girl in a blue coach, later identified as Zoya Nazyalensky. Alina settles into the military camp at Kribirsk, works in the Documents Tent with her fellow cartographers, and shares a quiet moment with Mal the night before the crossing.
The sandskiff enters the Shadow Fold and is attacked by a massive flock of volcra. Alina's fellow cartographer Alexei is carried off into the darkness, and Mal is badly wounded defending Alina. As volcra close in on them both, a blinding burst of light erupts from Alina, scattering the creatures and saving the skiff.
Alina wakes on the skiff and is treated as a prisoner, marched at riflepoint to the Grisha tent. There, survivors testify about the mysterious light, and the Darkling tests Alina by summoning darkness and cutting her arm. When she instinctively responds with a burst of sunlight, the Darkling orders her taken immediately to the Little Palace under armed guard.
Alina is forced into the Darkling's coach with Heartrenders Ivan and Fedyor for a frantic journey to Os Alta. A Corporalki Healer tends her wounds, and Fedyor explains that Alina may be a Sun Summoner whose power could destroy the Shadow Fold. Their convoy is ambushed by Fjerdan assassins, but the Darkling arrives with reinforcements, using the Cut to kill the man holding Alina hostage.
Alina rides with the Darkling's party through back trails toward Os Alta, exhausted and confused. During a quiet moment by a stream, the Darkling opens up to Alina about his ancestor the Black Heretic, the origins of the Shadow Fold, and his hope that Alina can help destroy it. They arrive at the double walls of Os Alta and the stunning Little Palace, where Alina collapses into sleep.
Alina meets Genya Safin, a Grisha Tailor sent to make her presentable before meeting the King. Despite her reluctance, Alina allows Genya to improve her appearance. Genya introduces her to the politics of Grisha hierarchy as the Summoners and Corporalki argue over who Alina should walk with in the processional to the Grand Palace.
The Darkling escorts Alina to the Grand Palace, where she is presented to the King. He summons darkness while Alina - guided by his amplifier touch - fills the throne room with brilliant sunlight, stunning the court. Alina meets the Queen, the creepy priest known as the Apparat, and is given a blue kefta after declining the Darkling's offer of his own black colours.
Alina wakes to her first morning at the Little Palace and dresses in her new midnight blue kefta with gold cuffs. At breakfast in the domed hall she is pulled to the Summoners' table by Marie and Nadia, who introduce themselves and warn her off Genya. Afterwards Genya gives her the promised tour: the library beneath its glass dome, the windowless corridor that runs behind the Corporalki anatomy rooms, and the Fabrikator workshops, where Alina is briefly introduced to David Kostyk, a reed-thin metalworker who silently hands her a set of tiny glass discs and barely looks up. They walk on past the lake and the Grisha school to a small stone hut hidden in the trees, where Genya leaves her. Alina knocks, lets herself in, and finds the harsh, ancient-seeming Baghra waiting in the heat. Baghra fastens a bony hand around her wrist as her very first lesson begins.
Alina's first day of lessons is a complete disaster. In Baghra's hut she feels the old woman is an amplifier like the Darkling, but the moment Baghra lets go, the power slips away and she cannot summon a thing on her own. Baghra shoos her off in disgust. Alina spends the rest of the morning buried under a towering reading list in the library, then drags herself to lunch and on to her first combat session at the West Stables with Botkin Yul-Erdene, the scarred former Shu Han mercenary. On the way she feels the Apparat watching her from a stand of trees off the path. Botkin runs the Summoners ragged, partners her himself for brutal sparring drills, and tells her she will come early to train with him from now on. That evening Ivan summons her from the Summoners' table and leads her through the war-room doors. Behind them the Darkling sits at the long table beneath maps of Ravka, simply asks how her first day has gone, and shows her a discreet servants' passage back to her room.
Alina struggles through weeks of fruitless training with Baghra, unable to summon her power on command while growing increasingly isolated from the other Grisha. She avoids practising with the Etherealki to hide her failure, and a disturbing encounter with the Apparat in the library leaves her unsettled when he gives her a book of Saints' lives and hints that she will suffer. She waits each night for a letter from Mal that never comes.
Zoya Nazyalensky arrives at the Little Palace and immediately targets Alina with veiled cruelty. During a sparring session, Alina trips Zoya, who retaliates with her Squaller power, breaking Alina's rib. While recovering in the infirmary, the Apparat visits Alina in the dark with more unsettling talk, and Alina asks Genya to find out where Mal has been stationed.
Alina discovers the Darkling arguing with Baghra and learns he plans to find Morozova's stag to create the most powerful amplifier ever known. Genya sends word that Mal is alive and stationed in Tsibeya but has not responded to any of Alina's letters. Heartbroken, Alina finally confronts the truth she has been suppressing - and in a breakthrough, lets go of her attachment to Mal and calls the light on her own for the first time.
Alina's life transforms after her breakthrough. She grows stronger, sleeps well, and eats with appetite for the first time. Baghra drives her hard, pushing her limits, while Botkin gives her a Grisha steel knife and Fabrikator-made mirror gloves. Alina grows close to Genya, enjoys the Grisha social life, and hears gossip about the royal princes - including the absent younger son known as "Sobachka."
On the day of the King and Queen's winter fete, Alina is too anxious to sit still and goes out to Botkin for extra drills with her mirror gloves. After a quick dinner she retreats to her room. Genya arrives in cream and gold and pins up Alina's hair, gently warning her about powerful men. A black silk kefta finally arrives, embroidered in gold and laced with a tiny golden sun-in-eclipse charm at the throat: the Darkling's colour and his symbol. They burst in on a furious Zoya to use her mirror, then sweep down to the Grand Palace. Alina and the Darkling take the stage for a sweeping demonstration of light and darkness that brings the court to its feet. He pulls her into an empty sitting-room off the corridor and kisses her hungrily, telling her that his men have spotted Morozova's herd, before footsteps in the hall force them apart. Slipping back to the Little Palace later, Alina runs into Mal in the entry hall: he is the tracker who reported the find. Their reunion sours into a bitter argument about the Darkling's symbol around her neck, and Mal walks out into the night.
Alone in her room after Mal walks out, Alina collapses against the bed and sobs. A soft knock at the door turns out to be Baghra, who seizes her wrist and hurries her down a hidden staircase to a bare servants' chamber, where she throws a pile of travelling clothes at her and tells her she must run tonight. Baghra reveals the truth: she is the Darkling's mother, and her son is the ancient Black Heretic who created the Shadow Fold. He never intended to destroy it; he means to expand it as a weapon, and the volcra were once the farmers and villagers caught inside it. Morozova's stag is no ordinary amplifier. Once the Darkling kills it and fashions a collar of its antlers, Alina will belong to him completely, her power his to wield. Stunned and shaking, Alina remembers his lies about Baghra and the Black Heretic, and finally reaches for the rough wool tunic and breeches Baghra has brought her.
Baghra rushes Alina out a side door with a travelling pack, a money bag, her knife and her mirror gloves, and sends her across the grounds shrouded in thin coils of darkness. Alina slips into the back of a departing theatrical wagon and is rattled out of Os Alta as the fete still glitters behind her. Once free of the city she takes to the Vy, then to hunters' trails and farm tracks, sleeping in haylofts and barns and eating cheese, bread and dried meat from a market in Balakirev. At a tiny church she hears the priest pray for the Sun Summoner and flinches her way out. Reaching the crossroads at Shura she chooses the Petrazoi mountain route over the river, but stops first in Ryevost to buy a bedroll and supplies. After dark a drunk tries to drag her into an alley; she blinds him with a mirror flash and drops him, only for one of the Darkling's oprichniki to lurch out of the tavern and recognise her. She bolts into the woods, hurls herself down a steep slope into a freezing stream, and is swept downriver into a slow pool, where she crawls into the brush and shivers until dawn.
Mal takes both watches and lets Alina sleep through the night in the lee of the rocks high in the Petrazoi. In the morning he simply says "Talk," and as they climb deeper into the mountains she tells him everything: Baghra's revelation, the Darkling's true plan for the Fold, the antler collar, and the Kerch ship waiting at Os Kervo. Mal cuts the Os Kervo plan to pieces and announces that they will turn north for Tsibeya to find Morozova's stag before the Darkling does. He admits he has deserted, that his unit had been ordered to hunt her, and that the only reason she got this far was because he led the others off her trail. Days of brutal climbing follow, then a welcome descent below the tree line, a rabbit roasted over their first fire, and a cautious stop at a village celebrating butter week. They join the crowd around the dom cart and Alina darts in to snatch a sweet roll, only to be cornered in an alley by two thieves who threaten to turn Mal in as a deserter. She blinds them with her mirrors and drops one with a knee to the groin and a brutal head strike, and they crash off into the woods together, laughing helplessly once they are safe.
North of the Petrazoi the pines give way to birchwood and the long, empty grazing lands of Tsibeya. Something between Mal and Alina has thawed and they talk easily as they walk, about court life, Grisha theory and the contempt the trackers feel for the King. One night by the rustling grass, Alina forces a promise from Mal: if the Darkling catches up with them before they find the stag, he must not let her be taken. Mal refuses, then breaks, and finally swears it. They scour the country around the outpost at Chernast for days. On a cold plateau in the lee of a boulder, as the first flakes of snow begin to fall, Alina coaxes a tiny shaft of light to warm them and Mal finally tells her that Mikhael and Dubrov are dead. His unit had hunted the stag past Chernast and across the border into Fjerda on a captain's reckless plan, and only two of the nine men who crossed came back. He volunteered, he admits, because he had stood by in the Grisha tent and let the Darkling take her, and he wanted to put it right. Quietly, Alina rests her hand on his arm in the falling snow.
Mal and Alina search Tsibeya for signs of Morozova's herd. After days of fruitless tracking and a heavy snowfall, Mal finally confesses his feelings for Alina, telling her he sees her now. They kiss, and at that moment the white stag appears in the glade. Alina cannot bring herself to kill the creature, and the Darkling's forces attack - an arrow strikes the stag, and the Darkling slits its throat.