The Bridge, Series 2, BBC Four / Hinterland, BBC One Wales

Why has Nordic noir been such an addictive novelty? Yes the plots are great, the locations moodily cool, the flat dialogue enigmatic. But in the end it’s all about gender. The detective who is a genius at work but clueless at life – we’ve seen it all before in a suit and tie and a battered mac. What’s different in equal-opportunity Scandinavia is that the dysfunctional crimebusters are beautiful bug-eyed Valkyries. Up north it’s the blokes who are the sidekicks.

First there was Sara Lund in The Killing. However much work she needed to do on her empathy skills, Saga Norén of the Malmö police department takes it to the next level. As the Danish-Swedish co-production The Bridge (****) returns, Saga is devouring manuals for tips on how to relate to a new live-in boyfriend, and teaching herself to laugh at others’ jokes – revealing a lovely smile of which it would be nice to see more.

We have all learned to genuflect at the altar of Nordic noir in recent years

Saga’s inability to lie played a key role in the climactic showdown last time round. She and her burly Copenhagen colleague Martin Rohde foiled a plot by a psychopath to blow up the eponymous thoroughfare which links Denmark and Sweden across the Øresund strait, but at great personal cost to Martin, whose son was murdered and who, exiled from the family home to a hotel, is still haunted by visions of the perpetrator. But he perks up no end when Saga walks back into his office and asks to buddy up again. For all Martin’s lingering anger management issues, it seems working in homicide is way better than therapy.

At the opening of series two the bridge was once more under threat, this time when an unmanned ship – Saga was most insistent that it was too long to be a boat - crashed into one of the struts. Upon inspection the vessel was found to contain five kids who, by the end of episode one, had started dying from pneumonic plague. By episode two, a quartet of young terrorists in animal masks were claiming responsibility and vowing to carry on killing as a protest against globalised farming methods. Their stated aim is to get people to support local farmers.

Their genocidal methods for publicising a relatively blameless ideological stance seem somewhat overblown, but then The Bridge goes big on supervillains with grandiose delusions. (So did The Killing III, come to that.) For non-Nordic viewers, the fact of two police forces collaborating across a border has less resonance (unless of course the cops are British and French). What continues to work beautifully is the bridge as a symbol of the thin but strong connection between hyper-organised borderline sociopath Saga and the shambolic but emotionally attuned Martin.

The question for the viewer is whether we’ve a grin as wide as Kim Bodna (wonderful as Martin) to see Saga back. After two hours Sofia Helin’s baffled stares and staccato monosyllables were starting to feel just slightly like hackneyed mannerisms. This may of course change as the plot – which involves school kids at both ends of the bridge – starts to thicken.

We have all learned to genuflect at the altar of Nordic noir in recent years – see The Tunnel, the Anglo-French remake of The Bridge, and the American Killing, not to mention the news that Borgen creator Adam Price and Michael House of Cards Dobbs are to collaborate. But the traffic is not entirely one-way. One series purchased by the Danish broadcaster DR is Hinterland (****), an intriguing and impeccably sullen crime series from Welsh-language broadcaster S4C. Its drama department is better known for the long-running soap Pobol y Cwm, but this is an altogether harder-hitting snapshot of rural Wales.

Set in and around Aberystwyth, Hinterland is that rarity in British television, a genuinely bilingual production, in that it was shot twice - in Welsh and then English. The Welsh version known as Y Gwyll was shown on S4C in the autumn. The English-language edition is due on BBC Four but is currently running on BBC One Wales, and is viewable on BBC iPlayer.

All four episodes riff on an old Welsh legend. The first, "Devil’s Bridge", takes the story of the canny old woman who tricked the devil at the scene of the famous old bridge spanning a dramatic waterfall in mid-Wales. In the present day, the hotel which overlooks the falls is a former home for children and the receptacle for some grim memories which the police investigate when the body of an old woman is found in a pool of blood. Richard Harrington (pictured above) plays DCI Tom Mathias, freshly transferred from the big smoke to get away - yes - from his bungled marriage, and teams up with DI Mared Rhys (Mali Harries). The landscapes are grimly wintry, as are the faces of everyone involved in this dark dark show. The Welsh tourist board can take comfort that Nordic noir has done wonders for visitor numbers in Denmark.

• 'It became two shows': watch Richard Harrington and Mali Harries talk about shooting in two languages