This page explains how to complete the Shadowbringers Main Scenario Quest "The Unbroken Thread".
This quest is available if you have completed the quest In His Garden.
Starting the Quest
Talk to Lyna in Lakeland to begin the quest.
Head to the Ocular
You can either teleport to the Crystarium or you can go southeast through the gate to the Crystarium. Use the Aetheryte or an Aethernet Shard to go to the Dossal Gate. Go east up the stairs and talk to the Crystarium Gatekeep and say Yes to enter the Ocular. There will be a cutscene.
Speak with Lyna
Talk to Lyna to proceed.
Speak with the Aspiring Amaro Tamer
Use the nearby Aethernet Shard to go to the Amaro Launch and go to the quest icon on the map. Talk to the Aspiring Amaro Tamer and there will be a cutscene.
Speak with Urianger
Talk to Urianger to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Urianger to accept the next quest: To Storm-tossed Seas.