Sophia may be the main character and pivot for much of the heroism going on but Lavinia is a hoot and deserved a book of her own!
Sophia's husband died a hero at the battle of Waterloo and she was granted a house and servants by the crown. Only now she has to deal with a blackmailer who is leeching her dry, as well as the Four Horsemen, two of whom are married in previous books (that I haven't read but want to). Sophia wants something more from life but fears what the blackmailer will do to others. She tries to strike a balannce but it's hard work. Meanwhile she finds herself attracted to Sir Nathaniel Gascoigne, again, he's looking forward to marrying off his sister and ward and having batchelor freedom for a while, but Sophia is distracting him.
It's light and fluffy mostly but it deals with a complex problem of the time.