The year is 1803 and England and France remain at odds. Hoping to break the English once and for all, Napoleon backs a ring of Irish rebels in uprisings against England and sends the Black Tulip, France’s most deadly spy, to the Emerald Isle to help. What the French don’t know is that England’s top spy, the Pink Carnation, is also in Ireland, working to shut the rebels down.

Meanwhile, back in England, Letty Alsworthy intercepts a note indicating that her sister, Mary, is about to make the very grave mistake of eloping with Geoffrey Pinghingdale-Snipe (second in command of the League of the Purple Gentian). In an attempt to save the family name, Letty tries to stop the elopement, but instead finds herself swept away in the midnight carriage meant for her sister. To each other’s horror, Geoff and Letty are found in a compromising situation and are forced into matrimony.  Then Geoff receives word that he must travel to Ireland to help the Pink Carnation, and he disappears immediately after the wedding ceremony. Letty learns of Geoff’s disappearance and, not to be outdone, steals away on a ship bound for Ireland, armed and ready to fight for her husband . . . and to learn a thing or two about spying for England.