This is one of my favorite books because it has one of my favorite romance tropes: the characters are already married. I'm always dumbfounded by people who complain about this type of storyline -- apparently it takes some of the fun out of it for them. You're reading romance, a genre in which the HEA is guaranteed (or I demand my money back). The journey is what makes the book worthwhile.
Anyway, Nick Gentry returns from a bit of an uneven appearance in Lady Sophia's Lover. I didn't entirely love him but I'm thinking maybe Lisa Kleypas hadn't quite figured how ruthless she wanted him to be so I can forgive it. It's three years later, and Nick has turned into one of Bow Street's best runners and commands the respect of even Sir Grant Morgan (Someone to Watch Over Me's hero). He takes a private commission to locate the runaway fiancée of Lord Radnor, Charlotte (Lottie) Howard who is hiding out with Lord Westcliff as a companion for the Dowager Countess. Nick convinces her to marry him to free her from Lord Radnor's really creepy clutches because her family won't help. And that's all in the first 50 pages.
The book is about their marriage and how Nick adjusts to the changes presented to him once he's married. Sir Ross Cannon (Lady Sophia's Lover) has petitioned for Nick to take up his title and birth name of Lord John Sydney, and Grant tells him that the runners are likely to be disbanded within some months. Lottie also has to contend with the creepy Radnor and her ridiculous family.
So the characters and the romance are amazing. I go back to this book often because I really like Lottie and Nick and the way Kleypas brings in a supporting cast of old and new characters. This is actually the first time we meet Lord Westcliff (which explains a huge issue I have, which we'll talk about in spoilers) but because I've read the entire Lisa Kleypas universe, he feels like an old friend here. I love seeing Ross and Sophia, though I'm surprised by how little we ever get to see Victoria, Grant's wife. She makes maybe two cameos, one in each book.
I thought Nick's back story presented some interesting obstacles for his marriage to Lottie and her resilience and naturally upbeat nature provide him a foundation to deal with the demons of his past and I like how Nick grows over the book and where he ends up at the end. Lottie's best stuff happens in the first half of the book--this is really Nick's journey.
The plot is probably where this book falls apart. It's almost dual plot -- and Nick's part holds up relatively well. His acceptance and reluctant embrace of his birthright feels real, and I happy with where it ends up.
It's Lottie's half of the plot that is crazy pants. Her family seems relatively one dimensional--her parents are basically selfish people who don't really get any kind of comeuppance and the resolution to the Radnor plot feels like maybe Kleypas built herself up to something she didn't know how to stop. It just kind of ends.
But this is a really good book with a good romance and does a good job ending the trilogy.