The emperor's coloured coat - John Biggins

This book follows the hapless Lieutenant Otto Prohaska in the waning years of the Austro-Hungarian Empire and finds Otto taking an ill-considered break from duties to engage in a mad fling with a Polish actress. After a desperate attempt to elude his lover's husband, he finds himself mistaken by anarchists as one of their own. Otto soon masters their code names and secret handshakes, but when he also learns of their plans to assassinate the Archduke Ferdinand in Sarajevo, his duty is clear. He must alert his superiors-now, if only he can find someone who will believe him!