Earl Derr Biggers 
The Agony Column [EPUB ebook] 

Written in 1916, the Great War very much plays a part in this tale of love, murder and spies. When a young woman catches the eye and heart of a young American in London, his only chance may be a bit of impropriety called 'The Daily.’
Geoffrey West catches the attention of the girl in question, and in spite of some misgivings, she agrees to read his personal correspondence. Her growing affection turns to dread and worry, however, as her heart is plunged deep into the plight of this young man desperately trying to prove his innocence after a murder occurs, and the possibility of it involving spies during wartime is broached.