During the World War I, in the British trench warfare at Battle of Passchendaele, an army private (rank), Arthur Hamp (Tom Courtenay) is accused of desertion. He is to be defended at his trial by Captain Hargreaves (Dirk Bogarde). Hamp had been a volunteer at the outbreak of the war and was the sole survivor of his company, but then decided to "go for a walk"; he had contemplated walking to his home in London but after more than 24 hours on the road, he is picked up by the Military Police and sent back to his unit to face court-martial for desertion.