Following the successful invasion of Britain by Hitler's troops in 1944, a battle-weary Wehrmacht platoon is despatched to the Welsh borders to patrol a small village. With the advance of the invaders, the local menfolk have melted into the mountains leaving their wives, mothers and daughters behind. Isolated in this women-centric community the soldiers - led by the sympathetic Albrecht (Tom Wlaschiha) - grow to value their distance from the fighting. Michael Sheen co-stars in an atmospheric drama that sees bitter opponents forced into uneasy cohabitation.
They certainly don't keep a welcome in the hillsides when a battle-hardened platoon of German soldiers arrive in a strangely quiet Welsh mountain community.
It's 1944 and Hitler's forces have victoriously crossed the Channel, taken London and are slowly consolidating their stranglehold on Blighty by pressing into the provinces. In this case, the Black Mountains.
For a start there are no men - they've taken flight, many joining the resistance. Secondly, the women they've left behind aren't In the mood for idle chit-chat.
They regard the invaders with dumb hostility despite the friendly overtures from cultured platoon leader Albrecht (Wlaschiha), a correct yet kindly commanding officer.
Gradually, as winter takes hold of the high farms, the women - including Andrea Riseborough's lonely Sarah - find themselves accepting the offers of help from the soldiers.
Some well-to-do, opportunist locals, although hardly Mosley's Blackshirts, go one step further and collaborate openly, reasoning they might as well accept things as they are.
Conversely, the German soldiers grow to value their isolation, secure in the knowledge that there's some nasty fighting going on for Britain's northern cities.
Director Amit Gupta, working from novelist Owen Sheer's screenplay, isn't tempted by big bangs and action setpieces, preferring to keep the narrative subtly human scale.
Michael Sheen has an all-too-brief role as a schoolmaster-turned-resistance leader who finds himself captured by the same soldiers who are seeking to placate the distrusting womenfolk.
However, it is Riseborough's deserted wife who commands the attention as she weighs up an unfolding situation that is as difficult to grasp as the Welsh mist.