The Finnish police are left baffled by a double murder in a Turku house – a former cop ritually sacrificed and his girlfriend shot in the head. Private investigator Jussi Vares (Antti Reini) is hired by the dead girl’s godmother to look for clues, and soon deduces that everybody has been looking in the wrong place. The police assume that the female victim was merely collateral damage; Vares realises that she was the real target, and her mutilated boyfriend merely a smokescreen. But why would anyone want to kill a highly-respected accountant?

The latest, and so far, last of the Vares films displays a visible stylistic shift from Hannu Salonen, a Germany-trained thriller director who would go on to make Arctic Circle (2018). It restores the comic-book freeze frames and mottos from the earliest films, and has a super-processed, enhanced look that fiddles with odd lens choices to stretch human figures or flatten out backgrounds. Audi is one of the film’s sponsors, but I don’t see any Audi product placement – perhaps it is worth more to the company to pay the Finns to repeatedly abuse, blow up and roll a bunch of Volvos.

Vares does some actual detective work, being ideally placed to notice that, like him, the murders sit on the borderline between the everyday and the criminal underworld. Through his druggie associate Antidote (Jasper Pääkkönen, presumably just before he got his role in Vikings), he is introduced to a council of criminal kingpins who bankroll ventures that fall outside the scope of the mainstream economy – deposits for contraband smuggling, down payments for getaway cars, and, if my own bitter experiences are anything to go by, mortgages for expats. His quest drags him into Finland’s black economy, with its own set of rules and protocols, and surreal daytime speakeasies where men sit on leather sofas and listen to Puccini. In other words, this the Vares series’ answer to Shadow Line, caught between the police and the criminals, each using their own methods in the pursuit of the murderer.

The new look and new director, not to mention the introduction of Shostakovich (Jukka-Pekka Palo), Vares’ self-styled patron from the underworld, could amount to a soft reboot for the whole series, since the novel Sheriff was the first of a sub-trilogy within the long-running novel sequence. Writer-director Salonen has made some brutal decisions with the regular cast, relegating Vares’ usual drinking buddies to a couple of cameos in the closing scenes, and recasting the journalist Ruuhio. Previously played by the clean-cut, ever-youthful Mikko Lempilampi, who presumably has better things to do shooting the same year’s Girl-King, he has suddenly been switched for my favourite Finnish actor, Mikko Kouki, who looks utterly ridiculous here as a gum-chewing slob with a man-bun. I don’t understand why they bothered to say this character was Ruuhio at all; it would have been surely been less disruptive to just give him a different name.

They certainly didn’t keep the original name of squeeze-of-the-week Milla (Karoliina Blackburn), a motorcycle-riding hacker who is swift to reveal to Vares that she only pretends to be a lesbian to hold off unwanted suitors. In the original book, she was known by the actionable pseudonym Harriet “Harry” Potter, the now-obscured origin of a joke in the script that points out the only thing she has in common with the schoolboy wizard is that they both like girls.

The publication of the English translation of the Sheriff book in 2015 permitted me the chance to read a Vares novel and to notice some asides that are not repeated in the film. For example, in the book Vares is momentarily troubled by a vision of himself, strapped to a bed in an asylum, while a nurse reads out newspaper headlines about catastrophic flooding on the Finnish coast. Is this a nightmare? Or is it a premonition about the events of the science fiction coda, Hard Luck Café? He is also brooding about a case that he failed to solve, the death of Mirjam in the snow a decade earlier, as chronicled in Frozen Angel. Meanwhile, an aside reveals that his friend, the author Luusalmi has only ever published a single book, making a mockery of numerous past claims about his erudition. It’s almost as if the chickens are coming home to roost in this late addition to the Vares canon, as both author and hero look back over their past adventures and try to make sense of them all, dredging up some of their earlier claims for a bit of tardy due diligence.

Sheriff, as the book repeatedly reminds the reader, is the Finnish title of the film better known in English as High Noon – one of many Western references buried within the Vares books. But Sheriff also seems like an attempt by author Reijo Mäki to engage with something that has been lurking at the edges of his world for years. Every now and then in Vares stories we get a glimpse of the wider criminal underworld, an entire wainscot society with its own rules, regulations and regulators. In Sheriff, Vares finds himself digging into the mechanics of one of the institutions of this shadow world, a criminal bank prepared to loan money at high rates to high-risk, illegal propositions. It’s not quite The Wire, but more John Wick, as Vares comes to realise the subtle codes he has ignored, inscribed on the very walls of some of the criminals he is chasing.

Jonathan Clements is the author of An Armchair Traveller’s History of Finland.