It's told through diary entries by fourteen-year-old Georgia Nicholson, and it's very, very funny. Georgia goes to a girls' school where they have to wear berets as part of their uniform, she has a huge cat named Angus who keeps trying to eat the neighbors' poodle, and she's crazy about a boy whose name she will eventually find out.
The story consists of small events, nothing earth-shaking, but they add up to a hilarious, surprisingly realistic account of a few months of Georgia's life. Her attitude is mostly what makes the book so funny. She's horrible in a relentlessly self-absorbed, can't-be-bothered way, but she never comes across (too much) as a jerk. That's a neat trick for the author to pull. It's a fast read, too; in fact, I read most of the book in the bath while I was getting over a cough, and I laughed so hard I coughed myself into a headache. But it was worth it.
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