While Lavie recovers from her injuries on the crashed Silvana, she dreams of her childhood with Claus, whose family moved to Norkia and became neighbors with Lavie's. Their fathers, Hamilcar Valca and Georges Head, immediately became best friends and teamed up as a vanship pilot and navigator. Claus's mother, Justina, took care of Lavie as if she was her own daughter. Valca and Head taught their children to fly a vanship and assigned them mock courier missions. Lavie recalls her father's two friends, a male vanship pilot and a female navigator, but cannot remember their names. One day, Valca and Head received an assignment to cross the Grand Stream to deliver a peace proposal to Disith and left with their two friends. However, Valca and Head lost their lives in the attempt, and Justina died not long after. In a separate dream, Alex Row sees the two vanships in the Grand Stream. After they were orphaned, Claus and Lavie began training to fly a vanship. They were eventually forced to sell their house to save the vanship and began training for courier missions. When Lavie finally awakens, she finds herself crying from the memories. Dio and Alister finally locate Claus and Tatiana near the field of Disith migration capsules. Claus is reunited with Lavie and informs her that their hometown of Norkia has fallen to Disith.

When Claus and Dio return to the Silvana, the crew is missing. When they go to search the bridge, they find that Delphine has captured Alvis and the ship. Tatiana and Alister sneak a transport carrying Sophia back to the Urbanus. Alex comes out of hiding to attack Delphine but is defeated by Cicada. Delphine takes Dio back to the Guild along with Claus, Alvis, and Alex, and orders that Exile be secured before they leave. On the Urbanus, Vincent promises Sophia that he will recapture the Silvana. When they return to the Guild, Dio is taken to prepare for the Rite of the Covenant. Delphine indulges in the world's rarest delicacies at dinner, causing Claus to become upset about her disregard of the hardships of the people of Anatoray and Disith. Dio is reunited with Claus and Alvis, but they find that his personality has changed and he no longer recognizes them as friends.

Exile enters Disith territory, followed by the Guild and alliance fleets. The alliance fleet loses one-quarter of its ships after Exile continues its indiscriminate attack, but Sophia orders it to continue at all costs to defeat the Guild. In the Grand Stream, Dio pursues Claus's vanship and relives their race at Horizon Cave. However, when he realizes Lucciola is not with him, Dio falls into despair and is thrown off his vanship by a gust of wind. Just as the alliance fleet falters in its attack, the Urbanus leads the remaining ships in protecting the Silvana as she makes a final attack at Delphine's ship. Alex, still a prisoner of Delphine, catches her off-guard and strangles her before breaking her neck. As the Silvana destroys Delphine's ship, Wina hears Alex's final words at her listening post. Claus and Lavie finally cross the Grand Stream into Disith, completing the feat that their fathers could not achieve. There, they find the remaining alliance fleet and bring Alvis to Exile. Claus recites all four Mysteria, to which Alvis responds, and Exile sheds its defensive cocoon to reveal a starship. Inside it, Claus and Lavie find their fathers' vanship and remains. The world they have been living in is revealed to be in the shape of an hourglass, and Exile takes Claus, Lavie, and many others to a new, conflict-free world. Claus and Lavie are reunited with Dunya and Mullin, the latter of whom has recovered from his injuries. They are joined by Alvis, Tatiana, Alister, Holly Mad-thane, and several children.