This page explains how to complete the level 90 Endwalker quest "You're Not Alone".
This quest is available if you have completed the quest Forge Ahead.
Starting the Quest
Talk to Alisaie in Ultima Thule to begin the quest.
Explore the Nekropolis
Go to the southeast part of the orange circle on the map and check on the sparkling Vantage Point.
Go just south of the center of the orange circle on the map and check on the Dusty Table.
Near where you checked the Dusty Table, check on the Tree-like Object.
Go to the northeast part of the orange circle and check on the Bar Counter.
Go to the west edge of the orange circle and check on the Vantage Point.
Go to the southwest part of the orange circle and go to the back wall of the structure, and check on the Rusty Door.
Speak with Alisaie
Go to the quest icon on the map and talk to Alisaie to proceed.
Speak with Alphinaud
Go southeast to where the orange arrow is pointing in the minimap. Talk to Alphinaud to proceed. There will be a cutscene.
Make your Way to Absolute Horizon
You can now only walk. Make your way northwest and walk through each of the shadowy figures. They will guide you to the end.
Speak with ???
Talk to ??? to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to ??? to accept the next quest: Endwalker. There will be a cutscene.