At the height of World War I, the front between the British and the Germans in northern France has hardened. But the Germans are preparing an ambush that endangers a British regiment of 1600 men.
The two British soldiers Schofield (George MacKay) and Blake (Dean-Charles Chapman) are now given the mission to warn their comrades, among whom is Blake's brother. The problem, however, is that the regiment is in enemy territory. And not only that. They also have only a few hours for the march.
Will they manage to rescue their comrades in time?