Saba has spent her childhood growing up on the desolate shores of Silverlake with her twin brother, Lugh. She lives in his shadow. Where he is laughter and light, she is brooding and dark — both in color and temperament. Their Pa, once a loving and attentive father, has grown morose over the last nine years, following the death of his wife during childbirth. Saba still loves Pa and is in awe of his ability to read the future in the stars, but she holds a grudge against her sister, Emmi, blaming her for their mother’s death. Lugh constantly reminds Saba to be patient and kind toward Emmi as she is only a child.
One night, as Lugh and Saba are skipping rocks along the shore of the dying lake, a strange red sandstorm approaches from the horizon. Pa manages to pull Emmi into the storm cellar, but Lugh and Saba are caught in it. As the storm dies down, five horsemen appear. Saba recognizes one of the riders as their only neighbor, a man named Proctor John.
The four strangers ask them if Lugh is the boy that was born at midwinter. Proctor nods. When asked, Lugh tells the strangers that he is 18. Proctor tells the men that he has been keeping an eye on Lugh for all this time and that he is definitely the boy for whom they are searching. The men shoot Proctor and chase Lugh as he tries to run away.
Saba calls for Pa. At first Pa seems reticent to help, as if he knew this would happen some day, but then he and Saba grab their weapons and run after Lugh. Pa tells her that he has only glimpsed the future, but he knows Lugh and Emmi will need Saba now, and many others will come to depend on her as well. Pa and Saba are thwarted in their attempt to free Lugh.
Against Lugh’s wishes, Saba promises to find him, no matter where they take him. The men ride away with her brother helplessly tied up on a horse. Pa is shot and killed.
Saba and Emmi make a grueling journey to the home of their nearest neighbor, a woman named Mercy, who had been a good friend of their mother’s. Mercy explains that the men who took Lugh were probably Tonton — spies and soldiers. She had seen them when she and Saba’s mother lived in a city called Hopetown. The city was nothing like its name, as it was a place of drugs and violence. As Mercy and Saba try to decipher why they would take Lugh, Mercy remembers that she was present for Saba’s and Lugh’s births. A traveler had happened to be there as well. He seemed very excited to see a boy born at midwinter.
He disappeared after Lugh was born, so he never knew of Saba’s birth. As Saba prepares to search for Lugh, Mercy gives her a necklace that belonged to Saba’s mother. The heartstone jewel will grow warm when the wearer is near her heart’s desire. She warns Saba to be careful in the Sandsea, which she must cross to get to Hopetown. It is a dangerous place where people get lost. Emmi begs to come with her, but Saba insists she stay safe with Mercy.
Saba does have her pet crow, Nero, to help her through the desert. The intuitive bird helps to keep Saba going in the right direction. The days are hot and long. One morning, she wakes to find that Emmi has “borrowed” Mercy’s horse and followed her. Saba is forced to bring Emmi with her as she has no water or food to survive the two-day journey back to Mercy.
Several days later, the girls are abducted by Miz Pinch and her husband, Rooster. Miz Pinch puts Saba in chains, shaves her head, steals her heartstone necklace and forces Emmi to work like a slave, while they all travel in their sand boat to Hopetown.
Rooster is kinder than his wife. He shows Saba a book with the picture of King Louis XIV. He tells how people used to worship the king. Rooster is the only person Saba has met who can read. Once they reach Hopetown, they bring Saba to the Cage Master. His arena is guarded by Tontons, but they allow Miz Pinch inside with Saba. Saba comes face to face with the leader of the Tontons, a formidable man named DeMalo.
As the man stares at her, Saba senses his voice inside her head, whispering that he knows her. The Cage Master welcomes Saba to his Colosseum. It is a place where young people are forced to battle each other in hand-to-hand combat. Fighters who lose three matches in a row must run the gauntlet through the audience. This inevitably ends in death as the drug-crazed mob tears the fighters apart.
Saba becomes a big draw in the Colosseum, never losing a fight and earning the nickname the Angel of Death. She makes no friends in the prison she is kept in, until she meets Helen. Helen does not want to fight; she plans to lose her matches so she will die sooner.
One night as the girls talk, Helen admits that her father was the stranger present when Lugh was born. She explains that he told the King about Lugh because he believes that if he sacrifices an 18-year-old born at midwinter, he will be invincible. The King lives in a place called Freedom Fields, and he controls the population there with chaal, an addictive drug. It is the same drug that causes the crime in Hopetown — the residents try to find ways to buy it for their own addictions.
Wrapped up in their conversation, the girls do not hear the guards come into the cell. High on chaal, they drag Helen outside. Saba knows she will not see her friend again.
Saba learns of a group of girls called the Free Hawks, fighters who live outside of Hopetown. She agrees to help their leader, Maev, free the prisoners in the Colosseum. Saba must lose three fights and run the gauntlet. The other Free Hawks will set up a distraction so they can free their friend Epona, along with Saba, and then the other prisoners.
After Saba loses the first fight, Miz Pinch’s son, Vicar, who is dressed like King Louis from the picture book and called the King, visits her. DeMalo accompanies the King, and, although he serves him, Saba can tell that DeMalo despises him. She again feels a strange connection between herself and DeMalo.
Out in the exercise yard, Saba meets an enigmatic and handsome young man named Jack. Her heartstone, which Emmi had returned to her, burns with heat when she comes close to him. That night, Saba dreams of saving him from a fire.
The Free Hawks’ plan works, but when they set the Colosseum on fire, Saba realizes that Jack is still inside, stuck in a solitary cell. She returns to free him, just as in her dream. After saving him, the two meet up with Emmi and the Free Hawks to escape Hopetown. Miz Pinch, Rooster and the King pursue them in their sand boat, but the Free Hawks are able to capsize it. It appears that the King and his parents are killed.
Saba, Jack and Emmi set off to find Lugh in Freedom Fields. Two of the Free Hawks — Epona and Ash — catch up with them and offer their help. Jack also enlists the help of a man named Ike. Before they reach Freedom Fields, the group must battle vicious creatures called hellwurms. Saba is severely injured in the attack, but Jack nurses her back to health.
The group arrives to Freedom Fields on Midsummer’s Eve, the night Lugh is to be sacrificed. They are shocked to see Vicar, the King, still alive. The group splits up so they can try to free Lugh and the other captives the King keeps to work his drug crop. In the ensuing battle, Saba sets the King on fire and manages to free her brother. She must then kill her friend Epona to spare her from Tontons.
When the group rendezvous at the appointed location, they discover Emmi is not present. She has been captured. The King orders a trade. He will free Emmi and everyone else for Saba. The group is surrounded by Tontons and Saba is about to surrender to save her sister when the Free Hawks arrive, led to the fight by Saba’s pet crow, Nero. Ike is killed in the battle, but the others survive.
Lugh, Emmi and Saba decide to head west. They take Ike’s adopted son with them. Jack heads in a different direction to tell Ike’s girlfriend of Ike’s death. He promises to find Saba when he has finished his task.