Reflections on the River

Once upon a time, in the far away kingdom of Nantu, a desperate King and Queen sought the help of a Witch. Although the Witch claimed no reward at the time, good fortune comes at a hefty price.
As the kingdom grew prosperous, so did the Witch's greed. Thrice did the Witch demand unreasonable recompense, but thrice was the Witch rejected. The visits stopped and for a short while, the kingdom knew peace. Until one day the Witch returned, demanding the kingdom's most prized jewel, lest tragedy befalls the land. Who will get their happily ever after in this fairy-tale?