Quest: The Tale of Captain Brage
You can find Captain Brage wandering around east of the center of the "Archaeological Site" (Area South of Lighthouse)
He will speak to you automatically and ask a riddle...the answer is 'Death'
Choose to bring him back alive - the game will automatically teleport your party to the proper authorities and the achievement will unlock after some dialog.
Note: The companion to this achievement will be lost on your playthough unless a save is reloaded.