Raubahn has received some promising intelligence asks you to convene at the Waking Sands.
This quest is available if you have completed the quest New Winds, Old Friends.
Starting the Quest
Talk to Tataru in Ishgard to begin the quest.
Enter the Waking Sands
Go to Vesper Bay in Western Thanalan and enter the Waking Sands. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
Speak with Yugiri
Talk to Yugiri to proceed.
Question Silver Bazaar Residents
Go outside and fly south to where the orange arrows are pointing in the minimap. Go to each of the quest icons to talk to Danyell, Kikipu, and Spotted Meadow.
Search for Meriel
Danyell said that Meriel is in the house closest to the market entrance (i.e. the entrance to the Silver Bazaar, so go into the house in the southeast of the orange circle and talk to Meriel. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
Speak with Alphinaud
Go outside and go to the quest icon on the map. Talk to Alphinaud to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Alphinaud to accept the next quest: Awakening in Ul'dah.