Book three in the Duchesses by the Numbers series or book nine in the Desperate Duchesses series though I have read all the books in both so it really does not matter. Eloisa is one of my favorite historical romance authors. She is excellent at period details plus her romances do not always follow a set formula which I am a big fan of. This one did not disappoint in either regard. The couple just happens to be two characters that are mentioned as kids and adults in other parts of the series making them previously known which is another big plus for me. This makes their romance so much more special, and I loved every minute of it. I was hooked from start to finish, and recommend it as a must read to all fans of historical romance. I give it 4/5 stars but would have been happy to give 4.5 if Goodreads had that option.