April 6, 1917. We see two soldiers asleep in a field, Blake and Schofield. Sanders, another soldier, wakes them up unceremoniously. As they assemble, Blake reads a letter from back home, but Schofield has received no mail. Blake talks about the fact that he thought the food would be better in the army, which is the only reason he did not become a priest. Schofield pulls out some ham and bread and gives some to Blake.
Blake tells Schofield that his leave has been canceled, but he does not know why. A sergeant tells the two soldiers that someone named General Erinmore wants to talk to them. When they go in, Erinmore asks Blake about his brother, who is fighting in the Second Battalion. Pulling out a map, Erinmore says that he wants Blake and Schofield to deliver a message to Colonel Mackenzie of the Second Battalion that would call off a scheduled attack that might compromise the battalion's safety.
He elaborates, saying that Mackenzie wants to attack the Germans, thinking that the British might be able to turn the tides, but that this is false. Erinmore believes that the German retreat is, in fact, a strategic withdrawal. Hence, Blake and Schofield must deliver the message before Mackenzie endangers his troops. Blake and Schofield must deliver the message before dawn the following day, as the enemy cut the telephone lines before they withdrew. "If you don't, it will be a massacre," he says, explaining that 1,600 men will die if they do not deliver it.
Lieutenant Gordon gives them some supplies and instructions, and they embark immediately. Schofield is nervous and wants to wait until it's dark, but Blake sets off, motivated to protect his brother and by Erinmore's instructions for them to leave immediately. They argue about what to do, with Schofield suggesting that it's best not to mess around when dealing with the Germans and that they do not need to be hasty, since they have enough time.
On their way out, Blake gets in a fight with another soldier, insisting that he has special orders. Schofield also reveals to Blake that he lost his medal from the Somme. When they get to the place where they are supposed to cross over, they ask for Major Stevenson, but a soldier tells them he was killed a few nights ago and that Lieutenant Leslie is now in command.
They go to speak to Leslie about their orders to cross from Erinmore. Leslie thinks that the mission is a misguided one, saying that the German withdrawal is a trap. Nevertheless, he gives them instructions, warning them to look out for craters, and tells them that they won't be able to send help until after dark. Leslie gets them a flare that they can send as a signal if they make it.
Blake and Schofield set off, passing by dead horses and other debris. They pass through a barbed wire fence and search for cover, jumping into a sap trench. Schofield looks at a wound on his hand from the barbed wire and they continue on through the mud and fog.
The film begins with two disillusioned young British soldiers who are ready to be done with their time in the army, exhausted by the poor conditions, the bad food, and the other drudgeries of war. The film shows us that they are not seasoned and polished career soldiers, but young men who chose to join the army because of the opportunities they thought it might afford them. Blake and Schofield are not exactly heroic-seeming; they more reactive than proactive, but they are dutiful and thoughtful soldiers nonetheless.
No sooner have we been introduced to the two soldiers than they are tasked with a heroic and dangerous task that exceeds their expectations for what might be asked of such men as themselves. General Erinmore sends them on a mission to deliver a message to the Second Battalion warning General Mackenzie not to attack the Germans, who have staged a strategic withdrawal. Blake and Schofield were talking about when their next leave will be and when their time in the army will end, when suddenly they are charged with an especially dangerous and intense task, forced to become heroes for the British army.
The two protagonists have very different approaches to setting off on their journey. While Blake, whose brother is in the Second Battalion and could die if they fail in their mission, is intent on leaving immediately and getting there as quickly as possible, Schofield is worried about no man's land and wants to make an informed decision about the best possible travel plans. He worries that to leave in the daylight will make them more vulnerable themselves, while Blake is singleminded in his desire to fulfill the mission. The two soldiers balance one another out, each adopting a different philosophy and plan in response to their mission.
The visual world of the film reflects the bleak nature of war. The color palette is drab and filled with the browns and grays of the trenches. The first shot of the film is one of the few aesthetically pleasant ones, as we see the two protagonists sleeping in a little patch of wildflowers, getting a momentary respite from their exhausting duties. Otherwise, the aesthetic world of the film is brown and mud-covered, a realistic portrayal of how gruesome and desolate World War I was. There are few bright colors or sunny skies.
The terrain that Schofield and Blake must cross is truly hellish. It is a foggy and ominous day, and the brown mud of the "no man's land" is filled with the dead carcasses of fallen horses and barbed wire fences. Even though their mission is not an explicitly difficult one in the military sense, it is a terrifying journey, one filled with the horrific fallout of the previous battles. Director Sam Mendes does not seek to show war as a glamorous or particularly ennobled situation, but rather as a gruesome nightmare, a horrific display of human darkness.