The books focus on Mildred Hubble, a young witch who attends Miss Cackle's Academy for Witches, a school of magic. Although well-intentioned, Mildred's clumsy personality leads the girl to disastrous situations, and she is thus considered the worst student in the school. The benevolent headmistress, Miss Cackle, is generally understanding, whereas Mildred's form teacher Miss Hardbroom thinks she just isn't trying hard enough. Mildred's friends include Maud Spellbody, a rotund, sensible girl who is always trying to avoid confusion, and Enid Nightshade, a practical joker who is more likely than Mildred to get them all into trouble. The three girls have a strong rivalry with Ethel Hallow, a high-born, snobbish and vindictive classmate.