- Main article: Queen of White Dunes/Script
In a flashback to two years ago, Lyon loses to Eirika in a duel, and Lyon laments his lack of strength. Lyon believes Grado needs one stronger than he to be its emperor, but Eirika assures him that his compassion will make him a strong emperor.
In the present, Eirika's group marches to Jehanna Hall; Seth reports that it has been occupied by Grado soldiers. Innes stats that, according to his spies, Lyon uses dark magic and will be a powerful foe, but they must rescue Queen Ismaire.
In Jehanna Hall, Ismaire confronts Carlyle—"Jehanna's most decorated commander"—as to why he betrayed them for Grado. Carlyle responds that he is in love with Ismaire, and that he does not care about the fate of Jehanna if he is with her. After the battle begins, Caellach and Lyon approach Carlyle and Ismaire. Caellach praises Carlyle for his effort, but takes Ismaire against Carlyle's wishes; Caellach assures Carlyle that he will not harm Ismaire as long as the Sacred Stone is destroyed. Lyon attempts to stop Caellach but is prevented by a bout of pain, and Caellach continues with Ismaire.
Elsewhere in the castle, Rennac works for Grado as a mercenary. Rennac expects the soldiers of Grado to defeat the enemy, allowing him to collect his pay without needing to fight. During the battle, Eirika or L'Arachel can talk to him. Rennac recognizes Eirika from his earlier travels with L'Arachel; Rennac offers to be hired for 9,980 gold, which Eirika can accept or refuse. Alternately, L'Arachel recognizes Rennac and tells him to accompany her; Rennac initially refuses, citing poor treatment and low wages earlier, but reluctantly complies with her continued insistence.
After the throne is seized, Caellach reaches Jehanna Hall's throne room with Ismaire and Lyon. Caellach demands that Ismaire hand the Sacred Stone over to him, deducing that she must have it; when she refuses, he attacks her, taking and smashing the stone. Caellach's attack did not kill Ismaire and Lyon frantically instructs him to help her, though Caellach suggests they leave her to die or kill her outright.
Eirika and her allies quickly set out to find Ismaire; in doing so, Eirika is left alone when Lyon teleports in front of her. Eirika pleads with him to stay and talk with her; Lyon apologizes for being unable to say much, and for being unable to stop the invasion of Renais. Eirika choses to believe Lyon and allows him to go. Before leaving, Lyon assures Eirika that he will always be her friend.
After Lyon departs, L'Arachel informs Eirika that they have found Ismaire, and they rush to her side. When they arrive, Seth informs them she will soon die. Ismaire calls out for her son, Joshua; if Joshua was recuited and is alive, he approaches her and apologizes for having left—if Joshua was not recruited or died previously, Ismaire laments that he is still missing. Ismaire explains—to Joshua or to Eirika—that the Sacred Stone of Jehanna is destroyed, and that there exists an unnatural "dark stone"; before she dies, she gifts the Sacred Twins of Jehanna.
If Joshua is alive, he explains that he left the palace a decade ago to better understand the people and become a worthy ruler. Joshua regrets leaving his mother despite this, and pledges the support of Jehanna against Grado.
Suddenly, a soldier bursts in and informs Eirika that the castle is on fire. The group quickly evacuates the burning building and into the desert, but Innes realizes that Grado meant to flush Eirika and her army out to fight. As Innes expected, Seth reports that two armies led by Caellach and Valter are closing in on their location; Innes suggests they retreat, as their army is exhausted and they cannot use the castle to withstand a seige. Innes wonders how Grado could spare such forces with Ephraim supposedly assaulting the capital, leaving the group unsure if Ephraim is still alive.
Beginning log
Thanks to the arrival of reinforcements from Princess L'Arachel of Rausten, Eirika and her allies successfully repel the Grado invaders. Still, Jehanna Hall remains under siege, on the edge of ruin. En route, Eirika learns that the hall has indeed been captured by Grado. To rescue Queen Ismaire and recover Jehanna's Sacred Stone, Eirika leads an assault on the royal hall.