The greedy Princess Elaine wants the Witch's cat because she believes it is magic.  The cat is captured, but then Elaine, in turn, is turned into a cat — a "cat princess" to be exact.  With the help of Morton, the magician, and Twirl, the jester, Elaine is saved and the witch is defeated.  More important, the princess realizes it was her greed that allowed the witch to transform her and becomes a much better person as a result.