A ray of sunshine on screen, Drew Barrymore isn’t going to suddenly make a grungy roller-derby movie. (Even the naughtier ex-Drew who once flashed David Letterman couldn’t swing that.) So she’s done something harder: made an intensely sweet roller-derby movie about letting your kids grow up happy. Whip It, Barrymore’s confident debut behind the camera, starts off in a desperate Texas nowheresville – an oven of blonde beauty pageants and crap jobs. Then, along with its teenage dreamer, the film sneaks off to an evocatively captured Austin and the world of cute but callous indie-rockers and snarly girls in kneepads. Finally, it ends with a kitchen reconciliation.

Along that exuberant trajectory, Whip It rights a few wrongs. First, there’s proof here that Juno’s Ellen Page is no mere snark in the pan. She uses her tiny frame to project vulnerability, coming alive as she flings herself into danger, shedding the starchy name Bliss Cavendar for the unlikely track moniker ‘Babe Ruthless.’ Second, in assembling her sassy sisterhood, Barrymore has given the criminally underused Kristen Wiig her first proper role, as a maternal roller with no-bulls*** sympathies.

The film pits parental hopes against the ambitions of youth, and manages to take both sides. Marcia Gay Harden is the picture’s treasure; watching her swell with concern at her daughter’s choices, you understand how hard it is to let go – even when kneepads are provided.