At the back of the family home, you'll find a dirt path that leads up a hill. Walk past the tombs, down some steps and veer off to the left to enter the forest. Walk a little further forward and you'll trigger the appearance of a witch who will ask the player a number of questions while altering your surroundings. Continue to move forward following the light and you'll eventually come to a tent with a note outside of it. Pick up the note and accept to unlock the achievement.