The Crimson Field follows a group of British doctors, nurses and volunteers who try their best to care for the many wounded soldiers at the front of the First World War. Three nurses take center stage: the sheltered upbringing Rosalie Berwick, who comes from a prominent background, Kitty Trevelyan, a strong personality and a bit of a mouthful, and Flora, the youngest and most enthusiastic of a group of volunteers. It immediately becomes clear that nothing could have prepared the girls for the atrocities they are about to witness.