'How the Light Shines' is a historical thriller set in the 1930s in England, France and southern Africa. It is an exciting tale of the attempted acquisition of diamonds by the German High Command and the British counter-espionage forces' attempts to foil them. For Germany, the re-arming of the nation has been given top priority. But in a small office on Piccadilly, Captain Morris Shuttleworth and his team at the Secret Intelligence Service have noticed the unusual journeyings to southern Africa of a member of the Abwehr. Meanwhile, romance and cocktails intermingle with each forces' ploys to outwit each other.