Beauty and the Bogbeast

The kids must seek out the river that rains upside down.  Once a year the river reverses it's course and rains upwards for 60 seconds.  And those who are in it can go whereever they desire.  Dungeon Master warns the kids that they 'must never touch the beauty that brings the beast,' but Eric picks a flower later in their quest that turns him into a bogbeast.  He then finds out that if he cannot undo the spell, he'll be stuck that way forever.  So the kids are now stuck in a dilemma, find their
way home, or find a cure for Eric.