The series followed Henrietta "Hettie" Hubble, (Mildred's younger cousin), through her years at Cackles Academy. Mildred is seen in the first episode accompanying her cousin to Cackles, before magically returning home. Hettie quickly becomes friends with Mona Hallow (Ethel's younger sister) and Crescentmoon "Cressie" Winterchild. The new enemy of Cackles is filled by Belladonna Bindweed and the sidekick is filled by Cynthia Horrocks. Miss Hardbroom and Miss Cackle return, and are joined by new members of staff Caspian Bloom, Miss Swoop and Miss Widget/Miss Nightingale.