Everyone is surprised to hear the Great Wizard is making an unexpected visit to Cackle's Academy. He has had a tip-off that the school is going rapidly downhill and it looks like non-magical Mildred is at the heart of the problems. Miss Cackle refuses to expel Mildred and waxes lyrical about her. The Great Wizard insists that Mildred should perform a magical display to prove herself. Creative Mildred conducts a magical potions choir, but it ends in disaster, leaving Miss Cackle on thin ice. With Miss Cackle not herself, and Ethel willing to do whatever it takes to get Mildred expelled, Mildred must somehow get to the bottom of things and prove to the Great Wizard that she deserves her place in the school.