Alina and her best friend, Mal, grew up together in an orphanage in the country of Ravka. Now they both serve in the army. Alina is a mapmaker, and Mal is a tracker. As they prepare to venture into The Shadow Fold, a supernatural tear of darkness in the land where monsters dwell, Alina finds herself jealous of Mal’s attention to other young women. She hides her feelings for him, convinced he only sees her as a friend.
In the morning, Alina, Mal and the army travel by special ships over the sands and into the darkness of the Shadow Fold. The ship comes under attack. Volcra, giant man-eating birds, swoop down, biting and clawing Alina’s friends and carrying them off into the darkness to eat. When one attacks Mal, Alina jumps to his rescue. She shields her friend with her body. When another beast attacks, the world is suddenly bathed in bright light. The volcra scatter as Alina falls unconscious.
When she awakens, she finds the ship has returned to town. She is dragged into the tent of the Darkling, the head of the Grisha. Grisha are people who have supernatural abilities to control the elements around them. Some manipulate fire and air. Others can heal. The Darkling can send a cloud of darkness, making those around him blind.
Witnesses come forward to testify that the incredible light that saved the army came from none other than Alina. She tries to refute them, but the Darkling clouds her in darkness and then cuts her arm. The pain causes light to explode from her again. She is heralded as a Sun Summoner.
Before she can say goodbye to Mal, she is whisked away by the Darkling, supposedly for her own protection. News that a Sun Summoner has been found will cause their enemies to kill her because only a Sun Summoner has any power over the Shadow Fold. If she can heal the rift, Ravka could again become a powerful nation.
After a harrowing few days on the road, in which Alina barely escapes with her life, she arrives in Os Alta, the country’s capital, and is promptly led to the King’s palace. Genya, a Grisha with the ability to change people’s physical beauty, helps to repair Alina’s haggard appearance. She has always suffered from a lack of sleep and lack of appetite. Genya subtlety makes Alina look well rested and highlights her hair. When presented to the King, Alina is only able to create light after the Darkling uses his power to intensify hers. The King and his court rejoice, hoping Alina will be able to restore Ravka to its former glory.
Alina trains as a Grisha, learning languages and combat, but she is hopeless when it comes to summoning her power on her own. She spends days in training with Baghra, an ancient Grisha with the ability to amplify another’s powers, just like the Darkling. Baghra is incapable of calling Alina’s powers to the surface until she causes Alina to find a forgotten memory.
Many years ago, when Alina was just 8, Grisha came to the orphanage to test both she and Mal for any power they might possess. Alina quickly understood that if she possessed anything, it would take her from Mal, so she hid her ability. By pushing it within her, it caused her to lose her health and appetite. Now that she is already separated from Mal, she allows her power to surface, and soon is able to have some control over it.
As she trains, the Darkling takes an interest in her progress. Although warned by Genya that he exerts a kind of pull over all the Grisha, Alina convinces herself that his feelings for her are special — a suspicion that is confirmed when he unexpectedly kisses her.
He tells her that he is searching for a mythical white stag, whose antlers can be carved into a necklace. The jewelry will serve as her personal amplifier. With the necklace’s additional power, she will be able to harness her own ability and heal the Shadow Fold and save Ravka.
On the night of the King’s special banquet in which all the Grisha will demonstrate their abilities before the court, Alina is surprised to receive new robes in the Darkling’s black color. By giving her such a gift, the Darkling is claiming her as his special disciple.
The two give a spectacular performance, and afterward share an intimate moment in a private room. Before he is called away to a meeting, the Darkling asks if he might visit Alina in her bedroom that night. Excited by his offer, Alina returns to the party before heading to her bedroom. She is shocked to see Mal in the palace halls. She has been writing to him for months without ever receiving a reply.
Mal is angry with Alina’s transformation into a Grisha. He assumes she has come to love the power and luxury that her abilities afford her. He loathes her obvious affinity for the Darkling. The two argue and part without making amends. Alina returns to her room in tears only to be surprised by Baghra.
The old woman insists Alina must flee the city to escape the Darkling. She explains that the Darkling is her son; he is also the madman who initially created the Shadow Fold. He wants Alina not to heal the rift but to enlarge it. The white stag has been found, and it is only a matter of time before the Darkling will have a necklace made from its antlers. If he places the piece around Alina’s neck, she will be forced to do his will, unable to stop him from using her power.
Alina runs away, heading for the sea and the hope of a life far away from the King’s court and the Darkling. Mal eventually tracks her down, but instead of turning her over to the Darkling, the two seek the white stag. If she places the necklace on herself, her powers will be increased, but they will remain in her control. Along the way, the two forgive each other and soon realize they are in love.
Alina makes Mal promise to kill her before he lets the Darkling take her back. They track the white stag’s herd and find it one cold morning. Although the beast’s power will not transfer to her unless she kills it, she cannot. Instead, the Darkling and his soldiers make the kill. He has a Grisha magically create the necklace. Alina begs Mal to honor his promise and kill her before the Darkling places it on her neck, but Mal cannot do it. They are taken as the Darkling’s prisoners back to the Shadow Fold.
Mal is placed in prison while Alina is forced to do the Darkling’s bidding. She begs the Darkling to spare Mal’s life, but he refuses. He will feed Mal to the volcra the following day. She spends the night speaking with Mal through his prison bars. In the morning, the Darkling arranges for delegates from several countries to ride a sandskiff with him through the Shadow Fold.
As the volcra begin their attack, he forces Alina to surround the ship with her light and make a path through the darkness. When the ship approaches the end of the Shadow Fold, the Darkling pauses and sends his power out into the thriving country outside of the darkness. Innocent people are swallowed up in the black cloud and devoured by the volcra. He then delivers his message to the nobles on the ship. They must submit to his rule over the land, or watch him destroy it with his powers.
Alina is helpless to stop the Darkling until Mal is thrown overboard and attacked by the volcra. Suddenly, a dream she has been having about the white stag makes sense to her. In the dream, as the stag is killed, Alina’s blood spills out of it, not the animal’s. She realizes that when she offered the stag mercy, it gave her its power.
She calls upon its strength and is rewarded with the ability to throw off the Darkling’s commands. She offers the people on the ship the opportunity to help her and defy the Darkling, but they are too afraid. Desperate to escape him, she throws herself overboard, uses her power to break the ship in half, and then plunges the nobles and the Darkling into darkness. She and Mal flee in her protective light, followed by the screams of the others as they’re devoured by the volcra.
Alina and Mal flee to the coast. They sell the gold pins Genya used to arrange Alina’s hair and buy passage across the sea. Although they hope to receive word of the Darkling’s death, they hear only rumors of war in Ravka. The two board a ship and sail to a new life. But Alina knows she will never be safe until the Darkling is destroyed.