Mildred and her friends try to join Ethel's Cauldron Club, but Mildred fails the initiation test. Fenella and Griselda, however, come to the rescue and the Dangerous Old Books Society - DOBS - is formed.
Ruby uses her appliance of science to unlock the secrets of the past - but disaster very nearly ensues and it is only thanks to Mildred's quick thinking that the Castle is saved.
Cackle's Academy takes part in a radio quiz show against girls from the dreaded Pentangle's School. Miss Hardbroom refuses to have anything to do with it, but in the end she saves the Academy from humiliation.
Miss Cackle's young niece, Gabrielle Gribble, comes to the Academy for teaching practice and Mildred Hubble and her friends teach her far more than she ever learned at WitchTraining College.
It's time for the dreaded Third Year Witch Project. Nerves are frayed and unlikely partnerships forged. The final demonstration in the Great Hall nearly ends in disaster, but all the girls work together to make the day memorable.
Miss Hecketty Broomhead returns to Cackle's Academy to take over while Miss Cackle goes to look after her sick aunt. Her insistence on rigid time-keeping proves to be her undoing, and Miss Cackle is welcomed back with open arms.
Cackle's Academy is staging a Pantomime for the Christmas season. Needless to say there is as much drama off-stage as there is on, and only with the help of a certain amount of magic does the whole production end as it should with Cinderella getting her Prince.
Mildred discovers that there is something which she is not worst at - drawing. Ethel, however, who can't bear the thought of anybody being better than her at anything, is determined to thwart Mildred. She very nearly succeeds - but not quite!
Mildred & the other girls notice Miss Drill is down in the dumps. They decide to give her a potion which will allow the non-magical Miss Drill to temporarily gain magical powers! Now the other teachers are trying to help Miss Drill hone her powers, while the suspicious Ethel & Drusilla try to prove that Mildred & her friends are behind it all!
There is rumour of a merger between Cackle's Academy and Camelot College, but Mildred and her friends devise a plan which is guaranteed to make Miss Cackle change her mind.
Love is in the air, or at least Miss Crotchet thinks it is. The visiting Professor Von Raffenberg seems to be smitten with her, but it turns out he is a conman, who is looking for the Lost Chord, which will grant the owner perfect luck! Some of the girls can see right through him, while others are conned into helping him.
As their third year grows to a close the girls sneak out to attend a local Fair. When Miss Cackle discovers them, she hears Mildred mocking her, the usually kind Miss Cackle punishes the whole school! Feeling this is unfair Mildred & Jadu decide to create a newspaper that mocks the teachers & has a list of their demands for how the school should be ran! Once discovered the two face expulsion!
Mildred & Jadu's expulsions are on the horizon & the other girls try to find a way to save them. The girls plan on running Maude for Head girl hoping to use their influence to save the two. When that plan falls through they decide steal Ms. Cackle's spell book & they end up creating a danger far greater than they've ever faced! Now it's up to Mildred to save the day!
