The story of the trench warfare of the First World War is well known. What is less well known is that the efficiency of the railway networks of both sides helped cause that stalemate. The programme describes the German Schlieffen Plan to use rail networks to invade France, and in the city of Liege how the Belgian railway workers resisted that invasion. On a light railway that still operates in the fields of the Somme, their extraordinary power and versatility is revealed. The programme looks at the remarkable work in France of the British Railway Operating Division and the bravery of its crews.