Earl Derr Biggers 
The Agony Column [EPUB ebook] 

Geoffrey West falls in love at first sight with a girl in a hotel breakfasting with her father. They’re all Americans, but the scene is London on the eve of the Great War. Both Geoffrey and his ladylove Marian are reading the personals (The Agony Column) of the Daily Mail. Later that day he has an idea to place an ad to catch her attention, and vows to send her a letter each day for a week to win her heart. Each letter becomes more interesting than the previous because West finds himself entangled in a murder mystery with new twists each day. To say more about what transpires would spoil the fun. The lightness of the story contrasts interestingly with the grim mood of England as Germany mobilizes.