New York-born Emma Morris Delagardie is a thorn in Augustus's side. An old school friend of Napoleon's stepdaughter, she came to France with her uncle, eloped with a Frenchman, and has been rattling around the salons of Paris ever since. Now widowed, she entertains herself by holding a weekly salon, and loudly critiquing Augustus's poetry.

As Napoleon pursues his plans for the invasion of England, Whittlesby hears of a top-secret device to be demonstrated at a house party. The catch? The only way in is with Emma, who has been asked to write a masque for the weekend's entertainment. In this complicated masque within a masque, nothing goes quite as scripted--especially Augustus's unexpected feelings for Emma.