After you help avert disaster in the Moraby Drydocks, Ghimthota entrusts an important task to you.
This quest is only available if you started the game in Limsa Lominsa, and you have completed the quest Victory in Peril.
Starting the Quest
To start the quest, talk to Ghimthota in the Moraby Drydocks in Lower La Noscea.
Deliver the Epistle to Baderon
Go to Limsa Lominsa and talk to Baderon in the Drowning Wench. It's north of the Aftcastle aetheryte. Hand over the arcane epistle and there will be a cutscene.
Next Main Scenario Quest
After completing the quest, talk to Baderon to accept the next quest: Feint and Strike.