The story ultimately is about follow one's heart and not settle for domestic dogmas. Ronia goes against the will of her father (who is powered by pride and "robbers prestige") and become friends with Birk, the son of the leader of the rivalling robbers band who lives in the other half of the fortress, on the other side of hell's gap. The news if this upsets Ronias father to the point that he stops recognising Ronia as his daughter... Together Ronia and Birk face both the hardship with life outside the fortress walls, as well as the evident separation from their parents all children must go through, as they grow older.