Fiennes explained of the plot, “Britain is 28 years into this terrible plague of infected people who are violent, rabid humans with a few pockets of uninfected communities. And it centers on a young boy who wants to find a doctor to help his dying mother. He leads his mother through this beautiful northern English terrain. But of course, around them hiding in forests and hills and woods are the infected. But he finds a doctor who is a man we might think is going to be weird and odd, but actually is a force for good.”