Mildred is given the responsible task of looking-after new girl Enid Nightshade who’s quite a handful. Enid ropes Mildred into all sorts of pranks and nearly gets her expelled, but when nasty Ethel Hallow locks them in the store cupboard, they hatch a clever plan to escape by broomstick. Miraculously they manage to impress headmistress Miss Cackle with their display and by the end, Mildred, best-pal Maud and new-girl Enid are friends forever.