It's a borderline secret quest, go to the sorrow's harbour, then into the scarlet keep and to the path towards the left, these when halfway in, instead of jumping down there will be a part on the top right side which'll take you to the place where you first met Ikora on the moon. You'll notice 4 statues there, you need to activate them in the right order (front right, back left, back right, front left). Once all four statues are lit, a chest will spawn in the middle of the room. Loot it to claim The Journey, the first step in the Emergence Exotic quest.