France, 1918 and weary Sam Clafin's company have rotated to the front, a six-day sojourn that will see his beleaguered troops expect a heavy German bombardment followed by a full-on attack. The tired British soldiers can barely man the appointed outposts but word comes down that a sneaky raid on the enemy lines to capture a solider and garner information as to the day of the attack is a must. Clafin selects Bettany and Butterfield to lead the team, the latter an enthusiastic but naïve young officer whose sister Clafin is promised to marry…

Over the course of its riveting running time The Duchess director Saul Dibb takes R.C. Sherriff and Vernon Bartlett's 1930 novel and kneads that historic Stiff Upper Lip into a grimace. A thousand yard stare, which would get past the German trenches here such is their close proximity, is added for good measure. There’s no "Put in a good show, old chap, and get the bacon delivered," to be found here. The trenches smell of the dead and faeces. The men are scared. David Niven wouldn't approve.

Sam Clafin, Paul Bettany and Tom Sturridge are at their wits' end, and not just because of the onion tea and the liver-based dishes served up by company cook Toby Jones. Sturridge is depressed to the point of suicide, scared to even step outside the relative safety of the bunker, while Clafin necks the whiskey to null the horror, He's angry, snapping at all and sundry – even high command – that the fates of men are based on guesswork over wine by pompous generals miles from the danger they so readily put others in. He transfers some of this frustration onto Butterfield because he reminds Clafin of the man he once was and will never be again. Butterfield’s youthful exuberance to keep the British end up irks him but his journey chips away at the jingoistic fever that swept him along to the recruitment office.

The perpetually underrated and frustratingly underused Paul Bettany does his best to be the typical officer class gent in front of the men, retreating to a book and a pipe during the quieter moments. But when "Uncle", as he's lovingly christened by the troops, is called upon for that dangerous mission his voice wobbles and his hands shake like the rest of them. The performances are flawless with Clafin holding steady in the lead role.

Dibbs' measured approach cranks up the tension, teasing out the inevitable German attack; apart from the odd pot shot pinging off a helmet the enemy is kept off screen, with the one captured German soldier bungled away and given a cup of onion tea before we learn anything about him.