Set a thousand years before the events of Oceanhorn: Monster of Uncharted Seas, this adventure unfolds across the kingdom of Arcadia, a vast realm of floating islands, ancient ruins, and warring peoples. A young man raised by Master Mayfair passes his trials and is finally named a knight. Returning home, he meets a girl named Trin and defends her when the sinister Mesmeroth and his Dark Troopers launch a sudden invasion. Fleeing to the safety of White City with the inventor Gen, the group learns that Mesmeroth intends to conquer all of Arcadia. To stop him, the knights set out on a perilous journey to gather the three Sacred Emblems of Sun, Earth, and Ocean and restore them to their ancient beacons, traveling to distant lands and the homes of peoples like the Owrus and the Gillfolk. Their quest carries them into deadly citadels and toward powers older than the kingdom itself.