Alphinaud will stay behind at the Rising Stones, and asks you to meet with Cid at the Skysteel Manufactory.
This quest is available if you have completed the quest A Brave Resolution, and have reached level 55.
Starting the Quest
Talk to Alphinaud in the Rising Stones in Revenant's Toll in Mor Dhona to begin the quest.
Speak with Cid
Go to Ishgard and use an Aethernet Shard to go to the Skysteel Manufactory Aethernet Shard. Go northwest to the small flight of stairs and go clockwise around the Skysteel Manufactory building. Enter the building and talk to Cid.
Speak with Estinien
Go to the nearest Aethernet Shard and use it to go to the Last Vigil Aethernet Shard. Talk to the House Fortemps Guard and enter Fortemps Manor, then talk to Estinien.
Visit the Seat of the Lord Commander
Go outside and use the Aethernet Shard to go to the Forgotten Knight Aethernet Shard. Go east through the door behind Firmalbert and talk to the Temple Knight Guard, and say Yes to proceed. There will be a cutscene.
Speak with Estinien Again
Talk to Estinien to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Estinien to accept the next quest: Into the Aery.