In the days after the Dunkirk evacuation in the World War II, recently commissioned Second Lieutenant Jim Perry (Niven), a pre-war Territorial Army (United Kingdom) private (rank), is posted to the (fictional) Duke of Glendon's Light Infantry, known as the "Dogs", to train replacements to fill its depleted ranks. He is joined by Sergeant Ned Fletcher (Hartnell), a veteran of the British Expeditionary Force (World War II).