Five hundred years ago, the Martials conquered the Scholars. Since then, the Martials have ruled the land with an iron fist, subjugating the Scholars into poverty and sometimes slavery. When the Martials murder 17-year-old Laia’s grandparents and her older brother, Darin, is taken prisoner, Laia escapes into the catacombs under the city in hopes of finding the resistance and enlisting their help to free her brother.
When she finds them, the resistance wants only to drug her and cast her away, but Laia invokes the names of her parents, legends and former leaders of the resistance. Their new leader, Mazen, agrees to free her brother if she will spy for them.
Meanwhile, Elias is getting ready to become a Mask, the most feared of all soldiers in the Martial army. But it is a life he desperately wants to flee. Over the past year, he has dug out a tunnel in the catacombs by Blackcliff, the Mask training school. He has kept his plans even from his best friend, Helene.
On the night before Elias’ planned escape, an Augur named Cain visits him. Although Elias has never believed the tales that Augurs are immortal and can see the future, he is unnerved by Cain’s uncanny ability to know his thoughts. The Augur warns him that even if he deserts, he will not be free and will become everything he hates — cruelty and evil.
The Augur also tells Elias that if he does his duty, he has the chance to be free of the Empire and become a great man. The following day, to his horror, instead of graduating from Blackcliff, Elias finds himself forced into the Trials. This is a series of life-threatening tests for four Masks. The winner will become the new Emperor. The runner-up will become his Blood Shrike, the Emperor’s right-hand man and guardian. The other two will die. Elias must compete against his rival, Marcus; Marcus’ brother, Zak; and Helene. This group is called the Aspirants.
In order to free her brother, Laia must become the slave of the Commandant of Blackcliff. The woman is notorious for her cruelty. She is also Elias’ mother, but the two hold no love for each other. The Commandant abandoned Elias to the desert to die soon after his birth. Tribesmen raised him. Tribesmen are nomads who still believe in the ancient magic of the world. Even after the Commandant beats her, Laia is still committed to spying on the Commandant and freeing her brother.
The Commandant tells the Aspirants that they will be tested for their courage, loyalty, strength of mind and heart, and cunning. The Aspirant who wins two trials wins the position of Emperor. The runner-up will be his Blood Shrike. The others, if not dead already, will be executed.
The Trials begin the next morning. Elias wakes up to find himself in a desert with a message that he must return to the bell tower by sunset of the seventh day. He wonders why the desert should test his courage, until he begins to see the people he has killed over his years training as a Mask.
As time goes on, he sees not only those he has killed, but also those he will kill in the future, including his grandfather and Helene. As Elias wrestles with the horror, he tells himself that he would never kill Helene. The vision the Augurs placed in his head fades and Helene finds him. Before the two can make it back to Blackcliff, Marcus and Zak attack them. Helene is severely wounded so Elias must carry her for two days. He barely arrives back at the bell tower before the sun sets on the seventh day.
Laia enters the Commandant’s office the following morning to serve her master. She is ordered to deliver letters. As Scholars are no longer allowed to read, the Commandant does not suspect that Laia is literate. She brings the letters to Mazen, but he is unimpressed. He warns her that she must get the resistance better information if she expects them to help free her brother.
Keenan, one of Mazen’s officers, escorts her back to the city. He is concerned for her safety as he can see that she has been beaten several times. She assures him that she can continue her assignment and leaves him to deliver one of the Commandant’s letters to a great weapon maker named Spiro.
While in his forge, Laia sees a strange creature of shadows called a ghul. It speaks in her brother’s voice and tells Laia of his torture and pain. Spiro chases the demon away. He explains that the ghuls left the world for a time but are now back. Not everyone can see them, and they feed off negative emotions. He informs Laia that he will consider the Commandant’s request for a weapon as long as Laia brings him more details. The Commandant later brands Laia for opening the letter.
The next night, Elias must face the Trial of Cunning. Fortunately, Cain has miraculously healed Helene, who was near death that morning. Together, the two friends face down assassins without much problem, but then they encounter efrits. Efrits are supernatural creatures made of sand.
Elias remembers a chant from his childhood about the demons. He urges Helene to sing, as it is supposed to make efrits flee. He then plummets from a cliff and loses consciousness. When he wakes, he is back at Blackcliff. Helene fought off the other creatures sent to kill them and eventually used her singing to heal his head wound. It is a skill people used to have in the past, but it is considered witchcraft now. Helene begs Elias to keep it secret as she does not know how she received the power.
Laia and another slave girl, Izzi, sneak out of Briarcliff to attend a festival in the village. Laia must also find the resistance and tell them news. Mazen insists that Laia must find a passageway into Briarcliff so they can then get her brother out of prison. Desperate, she agrees.
Keenen guides her back to the festival and the two share a dance. Laia finds herself drawn to the brooding soldier, only a few years older than herself. Elias, who secretly followed her, watches the two with jealousy. A Tribal woman approaches him. He recalls his past name and the speech patterns of the Tribal people easily and so does not reveal his identity to her.
After a few minutes, she whispers that she knows who he really is and that should he ever need help, her tribe will assist him. Once she leaves, Elias finds Laia again and, still disguised as a Tribesman, dances with her. They are attracted to each other, but the moment is interrupted when Martial soldiers raid the dance. Izzi recognizes Elias, and the girls must trust him to get back to Blackcliff unseen. When they reach the kitchen, the Commandant meets them. Elias pretends to sexually assault Laia so his mother will think that was the reason the girl did not answer her call.
Laia is sent to bring another message to Spiro. He tells her that her brother was his apprentice, a weapon maker for the resistance. When she informs him of Mazen’s news, that her brother is to be executed within the week, Spiro refutes it. Laia questions Keenen about the report, and he, too, suggests that Mazen may not be entirely truthful.
When Laia investigates a passage in the catacombs, Marcus brutally attacks her. He intends to rape her. Elias and Helene stop him, but Laia is badly beaten. Although Helene is jealous of Elias’ attraction to the slave girl, she agrees to sing the girl back to health. Without her ministrations, Laia would have died.
The third Trial is a brutal test in which Elias must lead his soldiers to kill Helene’s, Marcus’ and Zak’s armies. Their armies are made up of the friends with whom they have trained for years. When Elias orders some of his men to wound but not kill the others, the Augurs strike his men dead. He has no choice but to order the death of the opposing soldiers. In the end, Elias’ army wins the battle, but he takes no joy in the victory. Now he, Marcus and Helene have each won a trial, the final test of loyalty will decide who becomes Emperor.
Laia is taken prisoner by Cain and thrown, blindfolded, into a room. Elias is told she is his prize for winning the last Trial. He assures her he has no intent to rape her. Exhausted physically and emotionally from the battle, he wants only to talk and forget what has happened. He questions her about her family and assures her that her brother would not be in the prison Mazen claimed. Over the course of the night, the two console each other with their stories. Eventually, they share a passionate kiss, but Elias forces Laia away, not willing to let his desire go any further. Instead, they share memories for the rest of the night.
Elias must face the last Trial, that of loyalty. Laia is brought, bound and gagged, before him and the other two Aspirants. They are ordered to kill her as a traitor to the Empire. Helene attacks Marcus instead, but orders Elias to kill Laia so he can become the Emperor. Once Marcus is subdued, Helene again begs Elias to kill the slave. She then offers to do it herself, promising that she will free Elias of his oaths to the Empire once she becomes the Empress. Before he can refuse her, Marcus awakens and supposedly kills Laia. He is named the winner of the Trials; Helene will be his Blood Shrike. Elias is ordered to be executed the following day. Before the order can take place, news arrives that the old Emperor has been killed.
Laia, still alive, is told to pretend to be dead and is carried out of the arena by an Augur. Cain arrives and tells her she has a great destiny, but first, she must meet with the Resistance. She learns first hand of Mazen’s deceit when he orders her killed now that she is of no use to him. Keenen saves her life and gives her the code words to say to secure passage on a boat. He will meet her when it docks in three weeks and the two of them will save her brother. Instead, Laia gives the code to Izzi so she can escape the Commandant’s wrath. Laia and Cook, who is a former resistance fighter, raid the school’s armory and make several incendiary devices. They want to create a distraction, not kill anyone. After the explosions, Laia is able to free Elias. They set off together to free her brother and fight the Empire.