Some 17 years after "My Beautiful Laundrette", director Stephen Frears gives us another stunning cinematic portrait of London.

And it's not one that any tourist - or Hollywood studio - would recognise.

Frears' film focuses on the usually unseen world of the capital's illegal immigrants, the invisible people who keep its economy running smoothly.

Chiwetel Ejiofor's Nigerian exile Okwe is one such person. By day he drives a minicab; at night he's a porter in a hotel that's home to some shady goings-on.

When Okwe stumbles upon the hotel's dirty secret, he is placed in an impossible dilemma. A decent man, how can he do the right thing - given his precarious status - and still protect the people he cares about?

Scripted by first-time screenwriter Steve Knight (one of the creators, incidentally, of TV quiz show Who Wants to be a Millionaire?), "Dirty Pretty Things" works on one level as a gripping urban thriller.

What lifts the film out of the generic rut, however, is its political intelligence and compassion.

Frears has these qualities in spades. Unsurprisingly, he brings the best out of an outstanding multinational cast.

Admittedly, it's a bit disconcerting at first to see "Amelie" star Audrey Tautou as a Turkish asylum seeker (Okwe's best friend), but her unaffected performance soon wins us over.

Sergi López as the hotel's ruthless, scheming head porter, and Sophie Okonedo as a street-smart hooker, are also impressive.

But it's Ejiofor's subtle, understated portrayal of the dignified Okwe that ultimately holds the film together.

"How come I've never seen you before?" asks one of the few native British characters in the film. "Because we are the people you never see," replies Okwe.

"Dirty Pretty Things" opens our eyes.