January 1889. As the newest member of the Curiosity Club - an elite society of brilliant, intrepid women - Veronica Speedwell is excited to put her many skills to good use. During another investigation, Princess Gisela of the Alpenworld is found missing, just as Europe is on the verge of war. Having noted Veronica's resemblance to the princess, von Rechstein begs her to pose as Gisela for the sake of the peace treaty that brought the princess to England. Veronica reluctantly agrees to the scheme and must now attempt to keep the treaty intact while narrowly escaping assassination attempts.