How does one go about writing a movie that plays out in a single shot? And how does that differ from writing a traditional film script? Greatly, according to 1917 co-writer Krysty Wilson-Cairns. The up-and-coming writer had worked on two projects with Oscar-winning director Sam Mendes that never came to fruition before the Skyfall filmmaker called her up one day and pitched her 1917. Inspired by stories from his grandfather, the film would follow a soldier through his experiences in World War I, and would be incredibly personal and character-driven. Oh, and it would …