The narrative moves several years forward. Oro now considers Grim nearly “a friend.” They regularly spar and go out drinking together. Grim informs Oro that Egan is having an affair with Violet, the Wildling ruler and Aurora’s best friend. Egan attempts to deny the truth when Oro confronts him, not knowing about his brother’s flair. Oro demands that Egan either call off his engagement or stop delaying the wedding.

The narrative moves 10 years forward. Oro warns his brother that Aurora might secede from Lightlark if the Sunling king makes an enemy of her. In addition, Lightlark relies on Starlings for weapons manufacturing and energy production. These supply lines are especially important because Oro and Egan suspect that Grim’s father is secretly plotting another attack. Egan tells Oro that he will call off his engagement and give the crown to his brother because Lightlark “deserves a king who can put its needs first” (357).

Although Oro never wanted to be king before, he realizes that he has a chance to foster peace with Nightshade. Oro proposes that Grim kill his father and become ruler so that they can end the war between their domains. The friends shake hands to seal their promise.

The following morning, everyone in the castle is afflicted with a curse, and many die. Because curses are a Nightshade power, Oro believes that Grim is to blame. Grim tries to explain, but Oro’s flair determines that Grim is partly responsible for what happened. Oro attacks Grim, refrains from killing him, and vows to one day avenge himself by taking something Grim wants “more than anything else in the world” (362).

The narrative moves centuries ahead. Oro has been king of Lightlark for 500 years because Egan sacrificed himself as part of a ritual to reveal a prophecy about the curses. Oro invites Grim to the Centennial, a gathering of all six realms’ rulers in an attempt to break the curses. The Sunling king now understands that someone other than Grim used the heart of Lightlark, “the power seed of the island” (365), to cast the curses. Oro and his friends discuss the likelihood of Grim accepting the invitation. Because a prophecy suggests that a ruler must die to end the curses, Oro believes that Grim would be a fool to “walk into near-certain death” (367).

The narrative moves ahead to the Centennial. As Oro watches his fellow rulers’ arrive, he notes that the Wildling ruler is a young woman he doesn’t recognize. Oro witnesses Grim saving the Wilding ruler from falling off a cliff and wonders if Grim has changed. Later that day, Oro hears beautiful singing and traces the sound to Isla. When he applauds her, she startles at his presence and falls off of a balcony into the sea. Oro saves her life but leaves before she regains consciousness.

The curse on Wildlings is twofold; it compels them to kill anyone they fall in love with and to eat human hearts. Oro has a heart prepared for Isla’s dinner, but Grim objects and has it sent to the Wildling’s room. Afterwards, Oro questions Grim about his interest in the Wildling, but the Nightshade refuses to reveal how he’s connected to Isla or why he chose to attend the Centennial for the first time.

Each ruler who attends the Centennial assigns a challenge called a “demonstration” for the group to complete. One of the rulers chooses a duel, and Oro and Isla have a swordfight. The Sunling is taken aback by her beauty and skill, and he grows curious when she lets him win.

The curse that Aurora cast on the Sunlings causes sunlight to inflict deadly burns on them. Due to Oro’s status as the Sunling ruler, his health is tied to that of his realm. He and his domain have been cut off from the sun for centuries. He has a condition that manifests as fatigue, patches of blue skin, and reduced magical power. He believes that he will die soon unless the curse is broken during the Centennial. Enya urges him to “do whatever it takes to break the curses” and save himself, even if this means compromising his morals (383).

The demonstration set by Azul, the Skyling ruler, is a show of power, and Isla asks Oro to assist her. When she takes his hand, he feels a “shock […] right to [his] chest” (386). She blindfolds herself and uses a throwing star to knock his crown off his head. Although some of the Centennial’s attendees consider Isla weak because she hasn’t demonstrated any magical powers, Oro sees her as strong and confident. The emotions she stirs within him enhance his powers, and he turns a table to solid gold. This is the first time he’s gilded in centuries.

Oro learns that a group of Moonling nobles are planning to interfere with the Centennial, and he tells Cleo to prevent an insurrection. During their conversation, he learns that Cleo didn’t attend the last Centennial because rulers with heirs are barred from attending and she had a daughter, who has since died. Cleo also reveals that the oracle who predicted how to break the curses told her another prophecy: “She said five hundred years later, everything would change. Again” (392).

Isla sneaks out of the castle at night and visits a bar. Oro follows her and learns from the barkeeper that Isla is looking for a way to reach Moon Isle. The barkeeper also mentions that multiple realms seek the Wilding ruler’s death.

For her demonstration, Celeste challenges her fellow rulers to face their greatest fears. When Oro touches a magical mirror, he’s transported into a snowstorm. He freezes into a statue as the blue mark from the curse spreads, and the world falls into ruin around him. Oro hears his mother’s voice say, “Find your heart. Your fire has never left you. Find it” (398). He thinks of Isla and how her green eyes remind him of the ocean beside his favorite beach. The ice trapping him thaws as his feelings for Isla rekindle his hope for “a world to look forward to, a world worth fighting for” (399).

Isla’s demonstration asks the rulers to demonstrate the good they can do for the world. She uses Oro’s fire magic to severely burn her arm, then heals her injuries instantly with a Wildling healing tonic. Oro wonders what secrets she’s hiding that could explain her desperation to prove that she and her realm are powerful.

For her demonstration, Cleo turns an arena into an icy labyrinth and challenges the rulers to find golden tablets marked with their greatest desires. Oro isn’t consciously aware what his deepest desires are, and he hopes that gaining this information will allow him to overcome such “pretty distractions.” Oro is horrified to discover that his tablet reads “love,” as he fears repeating Egan’s mistakes and dooming his realm.

Oro instructs Zed to follow Isla to Moon Isle, where she sneaks into a library before escaping undetected. The king considers how to uncover her secrets.

Oro’s demonstration challenges the rulers to reveal their greatest secrets, which appear in cups of tea. All the other rulers forfeit the challenge, but Oro announces that he’s dying. Because Oro won more demonstrations than any other ruler, he gets to divide the leaders into pairs for the next phase of the Centennial, which involves seeking a way to break the curses. He pairs himself with Isla because Wildlings are experts on botany, and he seeks the heart of Lightlark, which he believes is bonded to a plant.

In a tense negotiation, Oro asks Isla to help him find the heart of Lightlark in exchange for his protection from the forces who seek to harm her. She agrees on the condition that she be allowed to choose one other realm that will be spared; Oro bristles because she suspects she’s shielding Grim and Nightshade. The king is surprised when she truthfully says she won’t tell Grim about their search. They seek the heart of Lightlark in an oasis but are unsuccessful. Although Isla treats Oro with scorn, he doesn’t regret choosing her as his partner.

The strain of Oro’s responsibilities, deteriorating health, and his feelings for Isla keep him from rest. His friends worry that Isla is dangerous. They take his mind off of his problems by playing a game called fireball, which involves using their elemental powers. Over the next several nights, Oro and Isla search in vain for the heart and slowly become closer.

In private, Azul tells Oro that he and his people have decided to sacrifice themselves unless another way to break the prophecy is found because they “would rather one realm die than doom all six” (439). Oro doesn’t want to entertain the possibility, in part because it would mean Zed’s death.

One night, Isla confesses her and Oro’s shared fear that they’ll never find the heart of Lightlark. He says that he fears his death because it will mean the deaths of thousands of others. He also tells her about his parents, and she says that both of her parents died before she had a chance to know them.

As Oro and Isla search a forest, she’s attacked by plants with fearsome thorns, and he rescues her. He lets her bite his hand while he tends to her wounds and feels “relief in offering her comfort” even though she draws blood (450).