Thu Nov 28, 9-10.30pm, BBC2

The Cold War was very much a battle of ideas. But once or twice, it threatened to turn hot, and many of its details remain sufficiently murky to make it fine fodder for dramatists. This Paula Milne film (adapted from a novel by Alan Judd) makes great capital out of the blurred lines between the personal and the political, between loyalty to self and to country and to concepts of truth in an innately dishonest milieu.

Events pivot around Charles Thoroughgood (Charlie Cox), a wet-behind-the-ears MI6 agent whose university friendship with Russian diplomat Viktor Koslov sees him fast-tracked into the middle of a urgent campaign to undermine Operation Legacy, a Soviet plot to destroy British infrastructure. But what will he find in this dark hinterland? Clearly peril and betrayal, but also shocking information about his own family and – via unhappily married espionage widow Anna (Romola Garai) – an insight into the emotional hazards of a life lived in such shark-infested waters.

Like most of Milne’s work it’s earnest to a fault, but also psychologically credible thanks to Cox and Garai’s expressive and committed performances. It also looks great: the permanent dusk of blackout 1974 is exploited to maximum effect.