Acker’s father, King Edmond, once again abandons his duties, and Acker is forced to lead an urgent war council meeting. At the meeting, Lord Tyreek reports that Kenta’s forces are retreating on the northern front, severely outnumbered by the enemy nation of Roison. Acker learns that their only ally, Strou, can’t send aid because although Maile is officially neutral, it’s blocking their ships.

After offering a temporary tactical solution for Tyreek’s battalion, Acker and his best friend and second-in-command, Hallis, decide on a new strategy: Attack the hillside where the Strou and Maile borders meet in the north to create a diversion and open a path for Strou’s reinforcements. This decision triggers a magical reaction in Acker because he’s under a blood oath to protect Jovie. She is his Bonded Match, and he’s drawn to her despite the fact that four years prior, she betrayed Kenta by killing every member of his father’s council and sparking a rebellion. Acker’s new plan directly conflicts with his unbreakable oath, an oath he can’t dissolve because it’s tied to his lingering love for the woman he also hates.

Acker leaves the palace through a secret exit and visits his friend Wells, the royal blacksmith. Wells is haggard and reveals that Acker’s father secretly ordered him to forge an unprecedented quantity of hearthstone weapons, rare armaments that are lethal to magic-wielding Heirs. Wells also reveals that his wife, Olivia, is pregnant and that he sent her away for her safety.

Wells tells Acker that Olivia told him that Jovie originally offered a truce in exchange for King Edmond’s life. Wells is furious that Acker refused and spared the king, blaming him for the ongoing war. Arguing that their enemies have shown restraint by not launching a full-scale invasion, Wells begs Acker to end the war by any means, insisting that Jovie will listen because she loves him. Acker, exhausted and unwilling to argue, leaves with their friendship strained.

Jovie surveys the battlefield after another brief skirmish with the Strou warriors, whose strategy is to harass her forces and distract from their true objective, which is to get soldiers and supplies to Kenta. General Samasu, or “Sam,” urges her to rest, but she insists on helping clear the field. She discovers a young Maile soldier, whom she recognizes, buried under an enemy corpse. Realizing that he’s still alive, she calls for the healer, Raina.

They discover that the soldier has been impaled with a black hearthstone ax. Jovie pulls the weapon free, but the soldier dies moments later. Sam helps her carry the body to the wagon for the fallen and sends her away from the field. As she walks through the quiet camp, she’s weighed down by the gazes of her soldiers and her own guilt over the war she started.

In her billet, Jovie removes her armor. Underneath her clothes, she wears a gyve of mangi stones (magic-dampening artifacts) to buffer her magic and the Bond connecting her to Acker. She avoids sleep due to nightmares and even more painful dreams of her past with him. Ruminating on her regrets, she wishes she had been able to convince Acker to come with her to Maile instead of joining Kai’s rebellion. She vacillates between anger at Acker and herself, believing that if he truly loved her, he would never have married Irina in a marriage arranged by his father.

Jovie falls asleep at her desk and dreams of a past conversation with Acker on a boat. She’s startled awake by her friend Messer, whom she almost stabs reflexively. Messer, a shifter she has known since they grew up together in Alaha, has flown in with an urgent message from Kai: Roison is ready to invade Kenta. Disturbed by the news, Jovie offers her cot to the exhausted Messer while she resolves to stay awake and write letters.

At a court dinner, Acker is disgusted by the Kenta council’s apathy toward dire war news, including 10,000 recent casualties. He receives a secret message informing him that the Maile sank a third of the Strou fleet using an eyun, a mythical creature that Acker believes is Jovie’s shifter friend, Messer. After burning the message to conceal it, Acker tries to leave, but his father intercepts him, insisting that he publicly escort Irina home to maintain the illusion of their strong alliance.

Once they’re alone, Irina’s subservient facade drops, and she threatens to tell Edmond that Acker has been having him followed every time he leaves the palace. Acker responds by physically intimidating her. Irina becomes emotional and reveals her desperation to end their sham marriage and return home to Strou. Acker gets her to their bedroom, where he offers a cold, partial apology for publicly choosing Jovie over her years ago, when he was Matched with Jovie despite his father’s arrangement with Strou. He warns her never to threaten him again.

In a spare room containing the belongings that Jovie left behind, Acker gives in to his compulsive need to connect with her. Although Jovie wears mangi stones to block their magical Bond, he has developed a tolerance that allows him to bypass her defenses when she’s asleep. After ensuring that Irina is asleep, Acker projects his consciousness across their Bond (in a process similar to astral projection). He finds Jovie passed out at a desk in a military billet, exhausted and dirty from battle.

A powerful bloodlust, rooted in his oath, drives him to lean in. He places his mouth on her neck, and he fights the urge to bite her and end their mutual misery. He’s snapped out of his bloodlust when Jovie groans in her sleep, and he jerks back. He resolves to see her in person soon and discover which feeling truly dominates her.

Hallis wakes Acker with news that Roison is clashing with Tyreek’s forces and that King Edmond is missing. A traumatized soldier arrives with a report from the front, revealing the shocking and unprecedented cause of the defeat: Trolls have joined the battle, clearing a path for Roison’s army. After debriefing the soldier, Acker convenes the war council. He orders all troops to fall back to defend the capital, anticipating a siege. When Tyreek demands a plan to retrieve his son Zion from the battle’s front, Acker orders Hallis to undertake a rescue mission to retrieve Zion.

General Sam informs Jovie that her mother, Evelyn, has ordered her to return home. Although she’s the queen now, Jovie still feels conflicted about her leadership role, and she’s aware that some soldiers resent her as the reason their brothers, fathers, and sons have died. Jovie refuses the immediate order. She compromises by agreeing to return in a fortnight.

After Sam leaves, Jovie studies a battle map, frustrated by the Strou’s impenetrable position in hillside caverns. She suddenly spots a tactical weakness: a ledge near a large cavern. Jovie immediately takes her map to Fredrich, a shielder, and proposes that they scale the cliffs at night and smoke the Strou out of their stronghold. Despite the reckless nature of the mission, Fredrich agrees to help her.

While scouting the enemy territory for their plan, Jovie and Fredrich are confronted by a furious Sam, who orders Jovie to return to camp. He reminds her of her promise to Evelyn to avoid danger, but Jovie asserts her command. Fearful for her safety, Sam reluctantly agrees to wait for a smoke signal and departs.

Jovie and Fredrich hide for the day and wait for the moment to begin their climb. Fredrich breaks his usual silence to comment on the loneliness of her position. This prompts Jovie to confess her guilt over the prevailing rumor that the war is her “lover’s quarrel” with Acker. Fredrich dismisses the rumor, reassuring her that it takes more than two people to start a war. He also says that fighting for love is a more noble cause than fighting for a greedy man’s power.

Jovie and Fredrich scale a cliff face to a cavern entrance of the Strou encampment. Inside, they discover that the enemy force is far larger than anticipated, with at least 500 warriors in that single cavern. Despite being vastly outnumbered, Jovie chooses to proceed with their plan. During the fight, she doesn’t use her magic, still buffered by the gyve, but they both use the magical protection of Fredrich’s shielding ability.

They kill all five of the guards, but when the last guard falls into the fire, it’s extinguished. The entire Strou force wakes up. Protected only by Fredrich’s shield, Jovie finally uses her own magic. She removes her mangi stones, which have been suppressing her power. Doing so unleashes her magic but also triggers her Bond with Acker, involuntarily pulling her consciousness into a brief, vivid vision of him reading a book and eating a grape. Fredrich slaps her back to awareness, and she discovers that her own body is now emitting a brilliant light. She channels the light into her sword, preparing to face the horde.

Acker uses the Bond to project his consciousness into the Strou caves, where he’s horrified to find Jovie and a companion fighting hundreds of warriors. In his invisible form, he kills a warrior to create a diversion that helps her. His projection is briefly interrupted by a worried Irina in his bedchambers, but he ignores her. Acker is both impressed by Jovie’s deadly skill with a glowing sword and disturbed by her fearlessness, which he believes is fatal.

When he realizes that his presence is distracting her, he pulls back, feeling helpless. He spends hours monitoring her through the tether of their Bond, even feeling her pain when she’s briefly wounded. After this prolonged vigil, Acker admits to himself that his concern isn’t just about keeping the oath; he realizes that he can never and will never abandon her.