A valiant, if not altogether successful attempt to tell a story of bravery in the First World War, 1917 suffers from an unreal feel, several flat patches and melodrama.

Roger Deakins’ evocative cinematography is its greatest feature.

At the height of the war, two young British soldiers, Lance Corporals Schofield (George MacKay) and Blake (Dean-Charles Chapman) are given a seemingly impossible mission.

They are asked to cross enemy territory and deliver a critical message that will stop a deadly attack by the Germans on 1,600 unsuspecting British comrades, who will be as good as lambs to the slaughter. Among them is Blake’s older brother, a lieutenant.

The idea for 1917 was sparked by stories that director Sam Mendes’ (American Beauty) grandfather, the late Alfred H. Mendes, shared about his time as a Lance Corporal in the First World War.

He also spoke about the colorful characters he met during his service.

In the year 1917, Alfred was a 19-year-old who enlisted in the British Army. Due to his small stature, the five-foot-four-inch soldier was chosen to be a messenger on the Western Front.

The mist over No Man’s Land – the unclaimed land between Allied and enemy trenches on the frontlines that neither side crossed for fear of being attacked – hung at approximately five and a half feet.

So that meant the young sprinter was able to carry messages from post to post without being visible to the enemy. In other words, he literally ran for his life.

While the movie’s premise should have made for a compelling film, I am not convinced it has turned out that way.

The events unfold in real time, so you get the appearance that the cinematography is one long tracking shot, although it isn’t.

Still, there are some shots that do go on for minutes on end without a cut.

Commendably, the script by Mendes and Krysty Wilson-Cairnstargets both a bigger picture and a personal story, but it is execution where the film is lacking.

While George MacKay tries to build drama and tension, he is hardly all that expressive.

And notwithstanding the ordeal that his character Schofield faces, he seems to be wearing a Teflon shield of invincibility rather than being made of flesh and bone. I say that in spite of a few relatively inconsequential war wounds.

I desperately wanted to build a greater affinity with him and Blake than I did. Put simply, I didn’t care enough and I really needed to. No welling of tears. Not even close.

Relatively little happens for the first hour, which feels stretched.

There are a series of encounters, or obstacles, along the way in an endeavour to build a more compelling narrative arc. Some are more farfetched than others.

I also felt there were times the score by Thomas Newman was way over the top.

So, in summary, Mendes had a fine idea and went with it, but the result is a mixed bag.

Rated MA, 1917 scores a 6½ out of 10.