Talk to Axelle, the Dock Manager, who is standing in the starting area of the Island of Dawn. She has a red exclamation mark over her head. Red exclamations mean story quests, while yellow ones mean regular zone quests.
Dawn's Early Light
You probably don't remember me, adventurer, but I was on the beach after that storm. Not long after you headed up the cliffs, the demons descended and everything went black. You're brave to come back here. Hardly anyone survived, and no one's seen Commander Elleon since you battled that Kumas Monster. We have control of the northern part of the island, but even here we aren't entirely safe. You should check in with Legate Lam. He can tell you how the search for Elleon is going.
Click on "Accept" to start the quest.
Your task is to report to Legate Lam. Legate Lam is standing a bit south of Axelle, near a red banner. Talk to him. He tells you:
You're exactly what we need, someone who's been here before and knows how dangerous the island can be. The new recruits see nothing but opportunity, but Elleon knew better. We never recovered his body, you know. If anyone could survive that demon attack, it'd be Elleon, and that's why we search.
You get gold and experience as your reward for completing the Dawn's Early Light Quest. This also gives unlocks the achievement "Expedition Relief" and grants you a new title, "Volunteer". To set your title, press "V" then locate the list of titles under "Earned Titles", and check the box to the left of the title you want to use.