Hint: The meaning of the riddle's "story" isn't really relevant to what you have to trade. Rather, there's just a hidden phrase embedded in the riddle you have to notice.
Solution (decode with rot13.com): Ernq gur yrggref ba gur yrsg bs gur evqqyr (gur yrggref ng gur fgneg bs rnpu yvar) sebz gbc gb obggbz!