There May Be Troubles Ahead:Bloodlands.

A black Land Rover is winched out of Strangford Lough in County Down, Northern Ireland, overseen by DCI Tom Brannick (James Nesbitt) and his assistant DS Niamh McGovern (Charlene McKenna). The discovery of the vehicle sparks a man hunt into its kidnapped owner, Patrick Keenan (Peter Ballance), but it also risks opening up some old, and still very sore, wounds for Brannick and his former colleague DCS Jackie Twomey (Lorcan Cranitch).

Keenan had been a former senior IRA member with connections to organised crime and an unlikely reputation as a womaniser. A photo of the large gantry crane, Goliath, from Belfast's Harland and Wolff shipyard, found attached to the car cause Brannick to visibly shudder. Brannick's wife Emma had died in the Troubles over twenty years earlier, taken by a contract killer who the police had nicknamed Goliath.

There is business that, to Brannick and others, remains, clearly, unfinished. Chris Brandon's Bloodlands (BBC4), soon moves from being a story about the hunt for Keenan and becomes a story about the hunt to discover Goliath's true identity. The inside knowledge Goliath clearly had about his victims suggests a police insider yet whenever you think you've worked out who that person might be there will be a shocking and mercurial (perhaps aptly for a show in which Jed Mercurio was an executive producer) plot twist which may leave the viewer completely wrongfooted.

People are rarely who you first think they are in this gripping drama, one that confidently inhabits the space between the action thriller and the police procedural. The Northern Ireland of Bloodlands is one of deep blue water, green green grass, windswept trees, and of birdsong but it's also one of desperately clutched soil, of errant priests worthy of Graham Greene's imagination, of suspicion, of appeasement, of body bags, of buried secrets, and of deeply held resentments. 

Political, sectarian, and personal. The religious schism, and violence, that scarred Northern Ireland and, to a lesser but still deadly extent, the UK towards the end of the last millennium is, in Bloodlands, played out, mostly, in the minds of those that lived through it. The reason Goliath wasn't pursued more forcefully in the late nineties was that the killings took place in the run up to the historic Good Friday Agreement and to do so would have jeopardised the chance of peace.

Which, now, Goliath does again. Atonement and redemption are given lip service but the main theme of Bloodlands seems more to be how sins can, if we are not careful, passed down through the generations. A callous act unpunished by the parent may, one day, see the child suffer the consequences. Despite the odd moment where, as my friend Ian commented, you think you've seen it all before (we're not suffering a dearth of gritty police dramas at the moment - and most of us are watching more television than ever), Bloodlands contains much tension and no shortage of genuinely chilling moments.

As Brannick, Nesbitt does A LOT of scowling, a lot of narrowing his eyes and staring meaningfully into the distance, and he does a lot of arresting. The crow's feet around his eyes have colonised his entire face and grown into suburbs and satellite towns of jaded repression on a brow furrowed with grief or even guilt at his own inevitable complicity in the situation he, and all his peers, have lived through.

He's not the only one. Cranitch, as Twomey, exudes a professional confident, almost political, air as the more senior policeman, at least until his own behaviour comes into question. As McGovern, McKenna starts bright eyed and full of idealism but events reveal that to be naive in the circumstances. The three main leads are all great but credit too should go to other cast members.

Lola Petticrew's great as Izzy, Brannick's daughter and a bright medical student who attends lectures taken by Tori Matthews (Lisa Dwan - also compelling), a trauma consultant with an uncertain back story, Birdy (Chris Walley) and Dinger (Michael Smiley) cope adequately in undemanding roles as fellow cops assigned to the case, and Heather Pentland (Susan Lynch) does well as a no-bullshit internal investigator down from Belfast.

As Keenan's wife Claire, Kathy Kiera Clarke carries a quiet air of menace birthed in decades of police brutality and being treated as a second class citizen and Ian McElhinney is great as Adam Corry. A man whose brother went missing, or was killed, at the same time as Brannick's wife. Surely another victim of Goliath.

Despite a score, and a scene towards the end, that could have come from a 1990s Sharon Stone movie (though, thankfully, Nesbitt spares us an exposed crotch shot), the tension rarely wavers throughout Bloodlands' almost four hour duration. As the walls start to close in on the various suspects and wrongdoers, you remain uncertain if justice will be done right to the end.

Which is surely what you want from a crime thriller. I can't help thinking that people who are from, or live in, Northern Ireland may get a little fed up with dramas about the Troubles. I imagine I would. But Bloodlands, to me, was idiosyncratic and addictive enough to make it worthwhile, even enjoyable - if often grim, viewing. Although I doubt I'll be booking a holiday in Strangford Lough any time soon.