'Alternative facts' is a buzzphrase for us all when considering what's happening in the news these days. But back in 1978, spy-fiction novelist Len Deighton was writing about an alternate history in which the Nazis had won the Battle of Britain in 1940 and were now goose-stepping and bludgeoning their victorious way around the streets of London. This 'what-if' drama sub-genre rarely fails to be either compelling or chilling, and in the five-part SS-GB it succeeds in being both.

With swastikas adorning the exterior of Buckingham Palace and Churchill having met his fate by firing squad, the Nazis' relentless march across Europe continues unabated. Within the corridors of the Metropolitan police, life goes on almost as usual: crimes still have to be investigated except now, the SS are kept abreast of developments particularly if a felonious act is related to the ongoing British Resistance movement.

Enter Detective Douglas Archer (Sam Riley) who continues to carry out his police duties despite the chaos and suspicion all around him. A decade on from his breakthrough role in Control, as Joy Division's tragic frontman Ian Curtis, Riley delivers a tasteful and nuanced performance as a man caught in the middle of two distinct factions (the SS keep a distrustful eye on him and the Resistance are targeting him for being a collaborator). Meanwhile at home, he is a single father whose boy wonders if dad can procure him this season's must-have accessory: an SS badge. Any notion in the viewer's mind that Archer might be a Nazi sympathiser is thankfully put aside by his love of the Blues.

The opening episode kicks things off near-perfectly, adroitly establishing the complicated world we are dropped into while offering scenarios both familiar (pub life, kids being cheeky) and unfamiliar (Hitler's head adorning British postage stamps). By the end of the first hour, the drama has managed to make the SS officers and Resistance members appear equally as shifty and untrustworthy, a tribute to this adaptation's ability to concoct a firestorm of credible paranoia.

SS-GB starts on BBC One, Sun 19 Feb, 9pm.