Exposing the unseen (or overlooked) atrocities and under-the-table dealings of an urban culture ultimately banks on shocking and numbing the audience in order to be thought-provoking.

And director Stephen Frears ("High Fidelity") seems to recognize and avoid this tactic in "Dirty Pretty Things," an appropriately titled tour de force of London's struggling immigrants.

A Nigerian runaway, Okew (played luminously by Chiwetel Ejiofor) is an illegal immigrant in the city who drives cabs during the day and works the front desk of a hotel all night, constantly chewing an herb remedy to stay awake.

Amazingly, not sleeping – there's not one shot of him lying down – doesn't phase his mental and ethical demeanor as he's increasling attuned to what's going on in and outside the hotel.

Called to fix a clogged toilet, he enters the bathroom to find a recently removed heart as the source of overflow. And when he asks his boss Sneaky (another appropriate description), he's cleverly instructed to report it to the police himself; Okwe can't because of his illegal status, and even his close friend (Benedict Wong) feels he's overreacting to an inalterable situation.

Okwe is thrown, only through exposure, into the underworld of the organ market. His Turkish Muslim roommate Senay (Audrey Tautou from "Amelie") follows her confidante into her own danger and exploitation, intensified by her striking beauty.

Written by Steven Knight, creator of television's "Who Want's to be a Millionaire?," the film balances across genres, without feeling like a poorly concocted, overachieving elixir.

For one, it's a petition for social change, with provocative imagery of an abused, abandoned population, but only to a certain (and very hypothetical) extent; the story is too contrived to be marked as having only political intentions and London's setting – a pleasantly soft glowing cityscape that contrasts the characters' unease – could well have been any metropolitan area.

And for another, Okwe and Senay's trudging through smoke and mirrors, always on the brink of danger, seems comparable for a thriller.

But the admirable thing about "Dirty Pretty Things" is that it can't be pigeonholed; both political critique and thriller-like-sequences exist to better define Okwe and Senay's relationship – one reliant on their mutual need to escape (Senay wants to go to New York to be with her cousin, while Okwe longs to see his daughter in Nigeria, from which he's banished).

While the movie proclaims "there is nothing more dangerous than a virtuous man," this only strengthens Okwe's image as a redeemable and selfless character.

Respectably, more than anything else the film offers, Ejiofor deserves accolades for a rich performance. It's hard to remember a character so reserved having the emotional fervor Ejiofor possesses, whose most profound statements are made with his eyes.

"Dirty Pretty Things" appreciates, or at least is a strong proponent for, the duality life has to offer, and though filmmakers have beaten the idea of life as terrible sweet, it comes off here as admittedly refreshing.

Extras include a short behind-the-scenes featurette and director commentary, both of which highlight Frears' skill as an actors' director.

"Dirty Pretty Things": AB

DVD Features: B