John Buchan 
The Thirty-Nine Steps [EPUB ebook] 

British writer John Buchan's The Thirty-Nine Steps is the first of five adventure novels to star Richard Hannay, a man with a remarkable knack for getting out of sticky situations, and indeed getting into them in the first place. In May of 1914, Europe draws close to war. Hannay has just returned to London when approached by a freelance spy called Franklin P. Scudder, who asks for his help. Scudder claims he has unmasked a German plot to pilfer British war plans and assassinate the Greek Premier, but Scudder himself is murdered in Hannay's appartment, leaving Hannay on the run and attempting to foil the Germans on his own.