Witnesses: A Frozen Death finale, BBC Four review - weirdo childbirth cult hits the buffers

It’s remarkable how pervasive the Scandi-noir formula has become, with its penchant for weird and perverted killers, labyrinthine plotting and intriguingly flawed protagonists.

Absorbing as it was, A Frozen Death did little to promote optimism about human nature. There are plenty of miserable real-life stories about abused women and abducted children, so it feels more than a trifle masochistic to sit down and subject oneself to more of it on the telly (Sky Atlantic’s new series of The Tunnel is heading in the same direction, and the two shows even have a French child actor in common). The theme here was particularly diabolical, featuring a bizarre cult that punished what it considered to be irresponsible parenting by kidnapping, “marrying” and forcibly impregnating women, whose own faithless lovers had been mass-murdered (not to mention deep-frozen). The resulting children were then kept in a kind of squalid coven living in decrepit caravans and a rambling derelict building.

The piece sought to generate for itself a kind of supernatural force by planting its roots in the bleak history of a children’s orphanage at Mont Saint-Michel (pictured right), the ancient commune off the Normandy coast which has been both fortress and prison in its chequered history. Catherine (Audrey Fleurot), feverishly trying to track down her own baby, spent some time in the Mont Saint-Michel library, poring over dusty tomes of ancient myths and legends which had once been perused by the children (including the show’s recurring poem about crazed mothers dropping their offspring). The child-abducting mastermind had adopted the symbol of the Minotaur, the classical beast which devoured human sacrifices delivered to him in his labyrinth. The Mont itself offered scope for some breathtaking aerial photography and landscape shots.

All this bogus mythologising was just camouflage for a bunch of repulsive freaks whose real ancestors were people like Myra Hindley and Jeffrey Dahmer, though perhaps a spot of medieval-style retribution involving disembowelling or red-hot implements might have been their most suitable reward. It was disappointing that the abductor-in-chief was allowed uninterrupted airtime to deliver his crackpot rants without being interrupted by a blunt instrument.

Pitched against these loathsome forces of darkness was our plucky detective-single mom Sandra Winckler, played with great empathy and determination by Marie Dompnier. True, she was prone to triggering most of the usual maverick-cop booby-traps – she systematically ignored every order from her superiors yet wasn’t sacked, and setting herself up as bait for the killer with no back-up is surely number one with a bullet on the Crass Policing Blunders chart. And, like Morse, Saga Norén and heaven knows how many more, she drives an amusingly antique car instead of the off-the-peg hatchbacks issued to everybody else. Oddly, so does her cuddly cop-partner Justin (Jan Hammenecker), who clanks around the landscape in a rickety Cadillac.

Despite its aura of downbeat verité, depicting the suburbs and wind-farms of northern France in all their unlovely functionality, Witnesses was quite happy to abandon logic when it felt like it. The way the killer managed to abduct, imprison, murder and freeze so many victims in so little time was beyond supernatural. The murderous nutter Geir Jansen (Yannick Choirat, pictured above) was time and again able to avoid detection despite spending much of his time strolling around in plain sight of the police. He was also strangely resistant to bullets and zombiehood-evoking drugs.

Still, it made for addictive viewing, albeit in frequently dubious taste. I fear things are only bound to get worse in Series 3.

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