Walter Vale (Six Feet Under's Jenkins) is a dry and abruptly brittle college professor unable to escape the  shadow of his vibrant late wife.

Grey and humourless, he is trapped in an academic rut, slugging on red wine and unsuccessfully attempting to learn the piano (his unimpressed tutor offers to buy it).

Reluctantly, he is despatched by his college to New York to deliver a paper on global affairs only to discover a pair of illegal immigants living in his pied-a-terre.

It turns out Syrian musician Tarek (Sleiman) and his Senagalese jeweller girlfriend Zainab (Gurira) are the victims of a scammer who claimed the apartment was empty.

However, rather than throw them out, Walter - revealing for the first time a sympathetic streak - invites them to stay until they can find somewhere else.

This streak expands to the width of the East River as Walter's mild curiosity becomes an all consuming passion as he gets to know the real people behind the Daily Express stereotype.

Writer-director Tom McCarthy's sure hand steers a story that could easily turn mawkish into a subtly revealing portrait of America post September 11.

Yet it couldn't be further from a hectoring "message movie".

No matter what view you hold on the vexed question of immigration, it's a chilling depiction of a Kafka-esque system into which good and decent people disappear.

At the same time McCarthy delicately stitches an unlikely - but extremely believable - love story which gently leads Walter to rekindling his own humanity.

None of this could have been achieved without performances which are truly exceptional - Jenkins, Abbass, Gurira and Sleiman don't just merely perform the roles...they vanish into them.

Elegant, intelligent and profoundly moving, it's a beautifully-crafted small wonder.

Tim Evans