After you retrieve the corpses and discover clues to the origins of the Amalj'aa attacks, Isembard asks you to question the locals for more clues.
This quest is available if you have completed the quest Unsolved Mystery, and have reached level 18.
Starting the Quest
Talk to Isembard in Camp Drybone in Eastern Thanalan to start the quest.
Deliver Isembard's Note
Go to the nearby inn (south of the Camp Drybone aetheryte) and talk to Ungust. If you watched the cutscenes during Into a Copper Hell, he will be a familiar face.
Hand over Isembard's note.
Speak with the Commonfolk
Leave the inn and talk to the Hungry Beggar nearby, then go northeast and talk to the Devious Derelict, then go north and talk to the Petrified Pauper.
Speak with Ungust
Go back into the inn and talk to Ungust.
Report to Isembard
Talk to Isembard to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Isembard to accept the next quest: A Proper Burial.