Mystery: The Spies of Hartlake Hall - R. L. Graham

London, 1917. When a man’s body is found deep inside Room 40, a highly secretive organization within the Admiralty, intelligence agent Patrick Gallagher is brought in to investigate. The man has no identification and was discovered in a room locked from the inside with no other apparent exit. Moreover, found in his pocket is a highly confidential telegram which would be political dynamite if it were to fall into the wrong hands.