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 they don’t know is that also in Ireland is England’s top spy, the Pink Carnation, who is 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 and is accidentally compromised. Geoff and Letty, to each other’s horror, find themselves forced into matrimony.

Then, Geoff receives word that he is to travel to Ireland to help the Pink Carnation and disappears immediately after their wedding ceremony. Letty learns of Geoff’s disappearance and, not to be outdone by her husband, 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.