Tracy (Evan Rachel Wood) is just a simple Valley girl with a dream of being cool. She lives with her single mom (Holly Hunter), an at-home hairdresser, and wastes her time studying for seventh grade until she meets motherless Evie (Nikki Reed), also thirteen, who defines cool for Tracy. That means hoochie tops, body piercings, shoplifting, drugs, bad boys, oral sex, lap dances and a three-way that Evie tries to negotiate with Tracy and a twentyish hunk (Kip Pardue). Every parent’s nightmare about how girls go wrong is packed into this movie and onto Hunter’s frazzled face as she watches her daughter deteriorate. The whole thing would stink of phony moralizing if Catherine Hardwicke, who won the directing prize at Sundance 2003, didn’t pack it with such raw vitality. Reed is strikingly good as Evie. She should be: She was thirteen when she wrote the semi-autobiographical script with Hardwicke, who used to date Reed’s divorced dad. But the revelation is Wood, 15, formerly of TV’s Once and Again, who makes Tracy’s transformation harrowing and haunting. She’s a live wire. Brace yourself for Thirteen — it’ll cause a commotion.