Cackle's Academy is a thousand years old and Hettie and her friends are horrified to learn the staff have not prepared a special celebration. They wonder if it has anything to do with the famous 'Curse of Cackles' which predicts that the school will crumble into dust if a witch flies around it anti-clockwise three times. The highlight of the teachers' plans is a solo performance of the school song from Dyllis Mustardseed, who is terrified by the very thought. So Hettie, Mona and Cressie make her a transformation potion - a potion which will make bad people good, and shy people confident. To their amazement it actually works, but inevitably Hettie cannot resist the temptation to try some of the potion herself - just to see what will happen. While under the influence of a potion, Hettie sets out to fulfil a curse which will destroy the school...
- The ending of this episode is sort of a tribute to the original series . First, when Dyllis starts singing the school song, a load of voices can be heard singing with her, and Hettie says it's "the old girls" singing. Although you can't really pick out any voices, you can hear a voice that sounds like Griselda Blackwood somewhere. Next, the end credits do not feature The New Worst Witch theme - instead, they start with the "Fearless witches never flinching" part of the school song, like the original series.