1917. Vienna. File clerk turned British agent, Fiona Figg, is more comfortable wearing a fake mustache than a ballgown. When a royal ball ends with a royal body in the middle of the dance floor, Fiona trades her dancing slippers for practical oxfords and sets out to investigate. As she tracks her nemesis, Fredrick Fredricks, from Vienna to the Austrian countryside, a hunting accident makes her rethink her loyalties. Can Fiona prevent Fredricks from striking again, save her own skin, and find a decent cup of tea, all before the enemy's emperor realizes she's a spy?