I was doing a children's literature course for university and this book was one of the recommended further reading texts. The protagonist, Harriet, may initially be perceived to be a pain in the neck because, as the title proclaims, she is a spy and spends her day to day existence invading the privacy of others, albeit surreptitiously, but, as the reader gets to know her, they realise that she's a lonely girl indulging in what she believes to be a little harmless fun, noting down her observations in her trusty notebook, but when the notebook falls into the wrong hands, that's when Harriet's problems really start. Generally, it's a very good story, and an inspiration to spies everywhere, whether amateur, like harriet, or professional. Highly recommended!