Following an accident, the headmistress of Lady Alfwynn's is advised not to return to school for the remainder of term. Mrs Leach is appointed as the new headmistress, and is able to start her duties the very next day... which is most unfortunate for Julia as she suffers a painful and humiliating caning from the new headmistress. It is the first caning of many to be dispensed by Mrs Leach, a woman who not only believes strict discipline is necessary to govern schoolgirls, but that her own opinions are the only ones that matter. She swiftly proves herself to be a tyrant, inflicting harsh punishments on dozens of girls, for offences real or imagined - mainly the latter. She even brings in her own daughter, Lucy Leach, as head prefect. Lucy proves herself to be every bit as obnoxious and unfair as her mother. All the girls, especially the class of 5B, are desperate to rid the school of the cruel headmistress and her harsh discipline regime. But how...?