The Bridge, BBC Two, series 4 review - Scandi saga is darker than ever

In the 1990s, which brought us Morse, Fitz and Jane Tennison, an idea took root that all television detectives must be mavericks. They needed to be moody, dysfunctional, addictive, a bit of an unsolved riddle. These British sleuths were all variations on a glum theme but the scriptwriters knew the limits. Make them suffer, but don’t put them through hell.

Then came Nordic noir, which actively pursued a policy of mentally torturing its protagonists. The Killing deprived Sarah Lund of an ability to form close bonds, and eventually evicted her from her own life. With every new series The Bridge (BBC Two) has been going a sadistic step further.

In the third series, broadcast in the UK two and a half years ago, Saga Norén’s inability to empathise was connected with an unhappy childhood and the death of her younger sister. By the end she was accused of murdering her own mother and came perilously close to copying her sister and throwing herself under a train. At the start of the fourth, Saga (Sofia Helin) was in prison and running the gauntlet of – her worst nightmare – other people, including hardened cop-haters. Never has she looked more like a frightened child. Solitary confinement came as a blessed release, although she also coolly exercised her right to conjugal relations when her Danish colleague Henrik (Thure Lindhardt) visited. Not that she’s his girlfriend or anything. “She wouldn’t like being called that,” said Henrik.

It’s not a great gig being Saga’s sidekick. The role has a high rate of attrition. “Martin’s in jail. Hana’s on one leg. She’s got it in for the Danes,” said Jonas, a new Copenhagen cop who doesn’t mince his words. (He’s also racist, sexist and homophobic, and is lustily played by Mikael Birkkjær, whom fans of Danish drama will recognise as the statsminister’s husband in Borgen and the serial killer in The Killing 2). This inventory of loss among Saga’s Danish colleagues also includes the death of Henrik’s wife, and the continuing absence of their two daughters who still haunt him day and night. By the end of the episode Saga had obtained her release from prison, but before she could make it through the door her neck was slashed and her blood was pooling all over the floor. This is what you get for not being relatable. (Pictured below: Thure Lindhardt and Mikael Birkkjær)The Bridge is back for one last turn of the screw. The Swedish-Danish co-production has spawned a wealth of franchised cross-border cop shows: not only The Tunnel which spanned England and France, but also ones set on the contested border between the USA and Mexico, and the frontier of Russia and Estonia; more are on the way. But if she gets out of jail alive, this is to be Saga’s final case. The BBC has honoured the occasion by moving The Bridge from the foreign drama ghetto of Saturday night on BBC Four, where episodes are always shown in double doses, to Friday nights on BBC Two.

It began with what should now be considered the show’s house style, an elaborate slice of contemporary grand guignol: a woman lay buried up to the chest under the titular link between Copenhagen and Malmö. A man in a balaclava picked up a stone from a pile and threw it at her head. And another one. The script benignly spared the audience the task of watching the 75 to 90 blows it took to murder Margrethe Thormond, the head of the Danish Immigration Service.

The various shady characters who have so far interested the Danish police include a young gay Iranian who is evading deportation and a violent taxi driver who is angry about his lack of access to his son. And there’s an iffy pair of Swedish twins, one a journalist specialising in far-left radicalism, the other bedding women in his name.

So everything’s darker than ever, and the only laughs so far are politically incorrect. Saga took up pottery in prison – “We had to choose a hobby,” she told Henrik, and pottery involved the least interaction with others. She gave him a cup. “A potter with cerebral palsy?” wondered Jonas on spotting this shapeless excrescence. The same cannot be said of the Øresund bridge, which looks more sleekly sinister than ever. For the first time the drama showed the point at which it plunges underground on the island near the Danish side. This script is following it into the depths.

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@JasperRees