The three books concerned themselves with the adventures of Tally Youngblood, who inhabits a world where children are surgically modified to be esthetically "perfect" on their sixteenth birthday, under a self-serving political system that uses strict social order to enforce total mental and political control over its citizens.
In Extras, we meet Aya, a citizen of a different city, one where the social order is determined by one's social rank, as calculated by a central computer that counts how many times your fellow citizens mention you. Aya is a would-be super-blogger (a "kicker" in local slang) who hopes to accumulate "face rank" (reputation) through breaking stories about famous "faces" -- highly ranked fellow citizens. This ambition entwines her destiny with the Sly Girls, a clique of fame-eschewing rule-breakers, and that leads her to discovering a secret so dark that it upsets the entire social order of her world.
Reputation economies -- where resources are allocated based on popularity -- are of great interest to me (I wrote a novel about 'em), and I'm as skeptical as the next writer about 'em, so I was really impressed with Scott's deft and thoroughgoing handling of the subject in Extras, a real exploration of all the social- and story-problems you can get out of a reputation system.
But as with all Westerfeld novels, it's not the great ideas that make them sing (though the ideas are great!), it's the wrenching pacing and deeply likable characters. Aya and her friends are some of the most interesting, flawed and inspirational people I've met in a young adult novel, making this yet another great Westerfeld to use in turning your kids onto sf. Link
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I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.