Cannes

Fish Tank

 (U.K.)

Wiry 15-year-old Mia Williams (non-pro thesp Katie Jarvis, mesmerizing) has been kicked out of school for unexplained reasons. She now spends her days drinking when she can get her hands on booze and dancing to hip-hop tunes in an abandoned apartment -- just upstairs from the digs she shares with her young mother Joanne (Kierston Wareing, from Ken Loach's "It's a Free World") and little sister Tyler (Rebecca Griffiths, also non-pro) both of whom Mia bickers with constantly.

When Joanne brings home her new b.f., hunky security guard Connor (the suddenly ubiquitous Michael Fassbender, "Hunger"), the attraction between him and Mia is immediately palpable, despite Mia's initially hostile attitude. Although an uncharacteristically good-tempered outing to the countryside vaguely promises that a happy family could be forming, Connor's manifest "grooming" of Mia is textbook pedophile behavior, even if Mia is just a year shy of the age of consent in Blighty.

There are no surprises about where this is heading at the pic's midpoint. Still, the last act throws in a few interesting curveballs -- including a revenge plotline incorporating an unusually believable portrait of how women try to get even -- that makes "Fish Tank" even more of a piece with Arnold's striking Glasgow-set debut, "Red Road." The milieu, on the other hand, is much more redolent of the working-class English council-estate setting of Arnold's Academy-Award-winning short, "Wasp."

Both features showcase Arnold's gift for evoking a woozy sensuality, particularly in situations in which characters' behavior teeters on the edge of transgressive. Witness here how the sound goes all whispery and slow-mo kicks in just a touch every time Mia and Connor get within touching distance of one another. It's both sexy and oh-so-wrong. And yet Connor isn't any kind of stock movie monster; only Catherine Hardwicke's "Thirteen" and a handful of other films have dared to evoke so frankly the nature of teenage femme sexuality, as young women test their power with a mixture of precocity and naivete.

Elsewhere, the pic's fine-grained detailing -- from the totally naturalistic way the characters talk here (steeped in obscenity) to the production design and the musical choices -- bolsters the sense of utter authenticity. Less naturalistic is the decision to lense (executed immaculately by Robbie Ryan) in what looks like Academy ratio, with film instead of digital stock. But although this is a little jarring at first, it makes a kind of emotional sense given the story's claustrophobic atmosphere.

A bit of trimming on the pic's two-hour running time might not have gone amiss, but it's hard to pick out any one scene in the film's generally tight script that could have been easily shed.

Camera (color), Robbie Ryan; editor, Nicolas Chauderge; music supervisor, Liz Gallacher; production designer, Helen Scott; costume designer, Jane Petrie; sound (Dolby Digital), Rashad Omar; supervising sound editor, Joakim Sundstrom; Reviewed at Cannes Film Festival (competing), May 14, 2009. Running time: 120 MIN.