‘Nudity seldom looks good, even on the young” was a maxim of the late Clive James that came into my mind while watching this enjoyable if self-consciously quirky black comedy, the debut feature from Tim Mielants, who so far has been directing TV, including episodes of Peaky Blinders.

In a Belgian naturist campsite, deep in the woods, Patrick (Kevin Janssens) is a middle-aged man with learning difficulties who lives with his elderly parents. They own the site but must cooperate with a management board made up of the regular nudist campers.

Poor Patrick lumbers sleepily around doing odd jobs; he is also having a borderline-abusive sexual relationship with a blasé woman whose husband is plotting to take over the camp. When Patrick’s father dies, his sense of shock and loss is transferred to the fact that one of his hammers is missing and he begins obsessively to ask all the residents if they know where it is. This bizarre displacement activity of quasi-grief opens up secrets in the group. The only person who seems to like Patrick is Nathalie (Hanna Hoekstra), the girlfriend of preening rock star Dustin (Jemaine Clement): they are the two non-nudist or nudist-refusenik campers.

The simple spectacle of nakedness is startling here: it looks like a kind of costume or fancy dress, a parody of the sexiness that most movies invite us to associate with having no clothes on. And it is extraordinary how many of the men here are so out of shape. There is an extraordinary scene when two very large, unattractive men have a fight in a caravan with cataclysmic results, their tiny, shrivelled penises as vulnerable as baby birds.

• Patrick is in cinemas and on digital platforms from 20 November.