Cryptic as ever, Urianger informs you that the as yet unidentified primal may soon awaken. He then reveals that an equally unidentified individual who is known to the Scions has taken it upon herself to investigate the being, and would solicit your assistance. Make your way to Wineport in eastern La Noscea, where the mystery maiden awaits.

You arrive at Wineport to find Alphinaud's twin sister, Alisaie, who has been conspicuous by her absence throughout your struggles thus far. She reveals to you that Castrum Occidens straddles a cavern formed in the wake of the Calamity, and expresses her desire to probe its uncharted depths. Fight your way through the imperial stronghold and seek a path down into the darkness.

You have found the entrance to the cavern in the innermost sector of Castrum Occidens. Report your success to Storm Private J'brohka.

J'brohka reveals to you that she is in the service of Alisaie, although she has enlisted with the Maelstrom for reasons of convenience. Her affiliations thus declared, J'brohka invites you to notify her when you are ready to enter the Binding Coil. Alisaie believes the truth of the Calamity sleeps within the cavern's unknown depths... but will she find the answers she seeks?

Having thanked you for keeping Alisaie safe from harm, Urianger bids you join the young Scion in reflecting upon all that you witnessed within the Binding Coil.
After laying Eorzea to waste in the catastrophic event now known as the Calamity, Bahamut was sealed deep beneath the Carteneau Flats seemingly by Louisoix, who was presumed dead. Even in his imprisoned slumber, however, the primal continues to drink of the land's aether, and in time will awaken to cast his dark shadow over Eorzea once more. In order to prevent a repeat of the Calamity─and to be reunited with her grandfather─Alisaie declares that she will investigate the two other enormous fragments of Dalamud that fell to earth. Aid her in this endeavor, that the realm might know true peace.

After sharing their findings with the Sons of Saint Coinach, Urianger and Alisaie have come to a conclusion: that the elder primal Bahamut can be banished into the aether if the colossal devices which hold him captive are deactivated. According to their information, the path to the second mechanism can be found in the North Shroud, where a gigantic fragment of Dalamud impales the ground. Make your way to Fallgourd Float and speak with Alisaie's assistant, Lieutenant Anaelle, to learn what dangers lie ahead.

Lieutenant Anaelle briefs you on the preliminary investigation made into the fragment, then requests that you speak with a colleague stationed nearer to the massive structure. Find the sharp-eyed private in Alder Springs, and listen to his more detailed report.

According to the private, the lack of an imperial presence meant that he and his colleagues were obliged to carve an approach to the fragment themselves. Though the ground itself is now passable, the scout warns you that much peril yet lies in wait. Hurry back to Lieutenant Anaelle, and rendezvous with Alisaie as planned.

You return to the serpent lieutenant's post, but it is Alphinaud, and not Alisaie, who meets you there. Your fellow Scion asks that you watch over his sister, and help her find her true purpose. Wasting little time, he then takes his leave, keen that Alisaie should not learn of his visit. Prepare and provision yourself well, and speak with Anaelle when you are ready to begin exploring the Second Coil of Bahamut.

Alisaie bids you return to the Waking Sands and deliver your initial report to Urianger, promising that she will join you as soon as she has set her troubled thoughts in order. Make for Vesper Bay.

Alisaie appears at the Waking Sands even as you complete your summary of events for Urianger. In the discussion which follows, the archon focuses his attention on the unexpected presence of Nael van Darnus, the defeated imperial legatus who once sought to bring the red moon Dalamud crashing down upon Eorzea. Urianger surmises that van Darnus's early efforts to establish control of the Allagan satellite inadvertently awoke the sleeping Bahamut, exposing the White Raven to the elder primal's irresistible will. Given the role played by such thralls in perpetuating Bahamut's existence, Alisaie declares that all must be found and eliminated─Louisoix's aetherial shade included. With that, she thanks you and departs, leaving Urianger to muse upon the value of uncovering a truth that promises so much anguish and sorrow...

You have scarcely exchanged two sentences with Urianger when Alisaie appears seeking the Archon's counsel on how to gain entry to the remaining internment hulks. Urianger suggests that she return to the connecting fragments of Dalamud in your company, in hopes that your presence will set events in motion, as it has so often in the past. In the meantime, the Archon promises to seek answers of his own. Make your way to the fragment situated at the Burning Wall in eastern Thanalan, and speak with Alisaie's assistant who has been reconnoitering the site.

To your disappointment, Alisaie's assistant reports that he has been unable to identify a viable path to the fragment's exterior, let alone a means to access its interior. Just as you are about to leave for Mor Dhona, where the next fragment lies, he adds that he has lost contact with his colleague there. Make haste to the Singing Shards, and ensure that the man does not come to harm.

You arrive at the Singing Shards just in time to prevent Alisaie's second assistant from coming to a sticky end. Unfortunately, the news he has for you is not good. If the fellow is to be believed, there will be no entering the fragment of Dalamud in Mor Dhona. Moments later, however, Urianger contacts you via linkpearl to notify you that he may have found a way to breach the remaining fragments. Make haste to the Ceruleum Processing Plant in northern Thanalan, where the Archon will furnish you with the details.

Urianger explains to you the method which he and certain other nameless individuals have conceived to reach the remaining internment hulks. Requiring that the laws of aetherial travel be bent to breaking point, the process entails considerable danger, but Alisaie is willing to take the risk. Meet her at the crystal formation known as Dalamud's Talons situated to the north of the plant.

Alphinaud arrives at Dalamud's Talons shortly after you do, revealing himself to be Urianger's mysterious collaborator. Having questioned his twin on the origin of her resolve, he declares that he will be joining your party on this descent into the Binding Coil. Speak with Erkenrad at the Ceruleum Processing Plant when you are ready to embark upon your mission.

Erkenrad acknowledges your readiness. At your word, you and your comrades will be transported directly inside the first of the two remaining internment hulks. Upon arrival, you must make your way to the main bridge and disable the coil responsible for Bahamut's regeneration. Spare no preparation and expect fierce resistance.

Having banished the elder primal Bahamut to the aether, you and the Leveilleur twins are transported back to Dalamud's Talons in northern Thanalan. Make your way to the Ceruleum Processing Plant, and report the mission's success to Urianger.

If anything, Urianger seems more relieved at your safe return than glad of your victory─though it is indeed a proud achievement. Thanks to you, Bahamut is no more, and with all his worshipers eliminated, the primal shall never again return to threaten the realm. As Alphinaud and Urianger embark on their diplomatic mission to conceal the truth of the Calamity, Alisaie bids you accompany her to the Burning Wall in eastern Thanalan. Having offered a prayer to all those who lost their lives at the start of the Seventh Umbral Era, Alisaie declares that she will embark on a journey to find her own reason to fight for the realm. Inspired by your fine example, she pledges to help those in need, and grow stronger in so doing.