Bong Joon-ho was last in Cannes with Okja, the Netflix produced story of a girl and her special pig. While that film was lauded by critics, I was left relatively unmoved. But with Parasite, the Korean auteur has surpassed himself. This time the action is no longer in a strange sci-fi world of Okja and Snowpiercer, but neither is it of the gritty police genre that we saw in the excellent Memories of Murder. Instead, the director has changed course again with a family comedy drama that is both laugh-out-loud funny and often bonkers but is also deeply troubling.

The action opens in a grotty basement flat containing a family of four. The two kids are desperately looking for a free wi-fi connection and Bong soon makes it clear that this is a family of grifters headed by the pater familias Ki-taek (Kang-ho Song) and his ex-shot-putting champion wife Chung-sook (Hyae Jin Chang). They might all be unemployed but they are extremely industrious when it comes to planning their next con. Their latest scheme arises via a friend of the son Ki-woo (Woo-sik Choi) who suggests that he tutor a wealthy young girl in English. A fake diploma is printed courtesy of Ki-woo’s enterprising sister Ki-jung (So-dam Park). This family has something in common with the one depicted in Kore-eda’s Shoplifters: they are a loving unit, perhaps a little unscrupulous yet essentially harmless. Or are they? Bong excels at shifting the viewer’s perception of these characters, but also of their victims.

Those victims are the wealthy Park family. Once Ki-woo is welcomed into the family home, it is short work getting the rest of his family employed by the Parks via ingenious manoeuvres involving peach fuzz and cheap knickers. The Parks are willing victims, readily opening their home to these con artists with little compunction, so cossetted are they from the outside world that it has made them forgetful of all its dangers. So should we feel sorry for the Parks? Their only crime thus far seems to be that they are rich. And what of the staff that Ki-taek and his clan have ousted? When the sacked housekeeper returns unexpectedly on a dark and stormy night, those sympathies shift once more.

This is quite literally an upstairs-downstairs tale as the action moves constantly from basement to bedroom in the fabulous Park home. Yet the upstairs-downstairs symbolism continues when Bong shifts the action outside. We see Ki-taek and his kids flee the mansion in the hills and race lower and lower into the depths of the city in one of the most spectacular and beautifully-shot scenes of the film. This is not just a story of some dodgy schemers but an analysis of class and inequality. The Park’s young son Da-song sniffs out the family’s relationship by stating that they all smell the same. And when Mr Park (Sun-kyun Lee) talks about Ki-taek he mentions that the latter never crosses the line, but his smell does. When he describes the smell as being like that of a packed underground train, his wife (Yeo Jeong-ho) remarks that she hasn’t travelled underground for years. Yet Ki-taek and his family live literally below ground.

The gap between the haves and the have-nots is a vast chasm that cannot be breached. Ki-woo has tried to enter university, but it is clear that this is a pipe dream. The fired housekeeper is hiding a secret in the Park’s basement which is the result of her family running foul of debt collectors who they will never shake off. Ki-taek talks of security guard jobs that “500 graduates will apply for”. He and his family are intelligent and enterprising yet they see no way of escaping their lot. For all its crazy energy and madcap humour, this is a film that takes a long hard look at Korean society where the split between the wealthy and the poor is immense.

It looks fantastic and is brilliantly written, with some zinging jokes. The ensemble cast of the two families is superb and it is hard to pick out just one great performance, though I loved Kang-ho Song as the dad. There are elements of Gosford Park here but the humour is very much of the Lavender Hill Mob variety. Bong Joon-ho stands a very good chance of walking away with a prize on Saturday and it would be very well deserved.