This page explains how to complete the level 80 post-Shadowbringers quest "The Search for Sicard".
This quest is available if you have completed the quest The Admiral's Resolve.
Starting the Quest
Talk to Alphinaud in Limsa Lominsa to begin the quest.
Speak with Alphinaud
Go west to the Aetheryte and use it to go to the Tempest Gate (Lower La Noscea). Go southeast to where the orange arrow is pointing in the minimap. Talk to Alphinaud to proceed. There will be a cutscene.
Speak with Alphinaud Again
Go northeast to where the orange arrow is pointing in the minimap. Talk to Alphinaud to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, talk to Alphinaud to accept the next quest: On Rough Seas.