THIS prequel seeks to explain how and, more importantly, why it all kicked off in a high-concept franchise that has already morphed from modest home invasion thriller to John Carpenter-esque actioner to politically charged survival thriller. The First Purge shows what happened when the eponymous event – where all crime, including murder, became legal for a 12-hour period once a year – was first introduced. The warped logic at play is that it will allow citizens to purge their anger and pent-up frustration.

Events take place long before it has become an established part of American life that has led to a monumental reduction in year-round crime. Initially, it’s pitched as an experiment to take place on New York’s Staten Island by the freshly elected New Founding Fathers of America (NFFA) who, explicitly-funded by the NRA, promise residents $5000 if they stay and even more if they “choose to actively participate”.

The protagonists include local drug kingpin Dmitri (a charismatic Y’lan Noel), more interested in protecting his product and money; anti-Purge activist Nya (Lex Scott Davis); and her impressionable younger brother Isaiah (British-born Joivan Wade). The latter is out for revenge after being assaulted by sadistic local drug fiend Skeletor (played with gleeful repulsiveness by Rotimi Paul) who has his sights on being the first one to kill.

All the while, NFFA chief of staff Mr Darragh (Arlo Sabian) and the architect of the Purge idea architect Dr Updale (a rather wasted Marisa Tomei) sit high and mighty within their remote glass tower, watching their so-called new great American experiment unfold before them on screens.

Depending on your viewpoint, the fact that the core outlandish concept has led to a now four-film-strong franchise is either a bewildering surprise or an inevitability of its power as piercing, unashamedly in-your-face social commentary on today’s United States of America.

The franchise has always been one that leans into cinematic exploitation territory, using controversial real-world topics to prop up what are essentially ludicrous, occasionally frightening – and, yes, sensationalist – Hollywood entertainment that audiences have flocked to every time. But so far, its reach has somewhat exceeded its grasp when it comes to wrestling with the social and political commentary that propels its general conceit ... until now.

The First Purge shrewdly uses real-world imagery in a way that the previous films didn’t, from Black Lives Matter protests to the torch-bearers of Charlottesville. “Make America Great Again” is the satirical vein that throbs throughout series writer James DeMonaco’s topical script. As heightened as the whole thing is, this is the closest to “believable” that it’s come.

The film does a solid job of marrying what it’s trying to say about the anxieties of living in modern-day America with the pulsating anarchy, thrills and disconcerting energy of the Purge’s perverse spectacle.

More than any of the previous three films, it specifically grapples with the socio-economic implications for low-income citizens who are less financially capable of protecting themselves. It could be viewed as wide-scale coercion as people take the financial bait because of their economic dire straits, as well as wider commentary on whether it’s really just the fear of legal repercussions that hold people back from killing.

It provides enough moment-to-moment surprises and flinch-worthy slashes of violence to keep you on edge – it’s grisly and unpleasant at times, there’s no doubt about it – as much as it unsettles when witnessing the spiralling depths of hedonism with which some of the participants engage in the experiment.

It doesn’t quite reach the franchise high of the second film, aptly subtitled Anarchy, but it manages to get its points across with a refreshingly keen sense of hot button topicality fuelling its rage. It conjures an ugly world – just imagine if it was real.