I can't overstate how much I adored this book. It takes place during the Napoleonic Wars(the Regency era). The hero, James Meyer aka James Nathanson, is a spy who was recently betrayed, and escaped after being tortured. He's pretty much in a fog of apathy and depression when his family arranges the marriage between him and Eloise. It's a little more difficult to understand why Eloise goes along with it, except that her grandmother, who is the family matriarch, is in favor of it. Also, they're both Jewish and therefore Eloise's selection of eligible men is limited, she can't really circulate in society, so this looks like her best chance to get married. One thing I liked about this book is that both James and Eloise come from loving and well-meaning families. James's family is hoping that having a wife will help him snap out of the funk he's in, and Eloise's parents want to see her settled with someone of good family, plus the prospective groom is young and handsome. They are just beginning to become friends and get to know each other(despite a major misunderstanding which is mentioned in the plot synopsis above), when James gets a message from the woman in Paris who betrayed him and caused him to get captured before. I'm just going to call her EBS, short for Evil Blonde Shiksa. Because he still has some sort of obsession with her, even though he is beginning to fall in love with Eloise, and also because Eloise's grandmother in France appears to be on her deathbed, they end up traveling to France together.
Now, here is where the real fun begins. James ends up in prison(betrayed by EBS again, surprise, surprise!). Despite the secrets he kept from her(she didn't even know he was a spy when they got married) Eloise decides it's up to her to get him out. I love it when the heroine has to rescue the hero, and from this point on, the book becomes a total tour de force. The way she manages getting him out of the French prison is simply so well done, plus, then they have to escape back to England. I also love road stories, and a lot of the rest of the book involves their adventures sneaking around the countryside with the secret police hot on their trail.
By this point James has realized what an idiot he was, that he loves Eloise, and that major groveling will be required. She's in love with him too, but what she demands from him before she'll take him back is way beyond groveling. I'm not going to give away what she makes him do, but suffice it to say, it was an extremely satisfying conclusion, and a HEA unlike any other romance I've ever read.
If you like to see the heroine rescuing the imprisoned hero, here's a short list of other books using that plot device:
The Perils of Pleasure by Julie Ann Long
No Longer a Gentleman by Mary Jo Putney
Vienna Waltz by Teresa Grant
The Forbidden Rose by Joanna Bourne.
They're all great books and I recommend them, but what made The Spy's Bride so enjoyable was that in all those other books, the heroine is some sort of spy or expert at escape. Eloise, on the other hand, is just a nice Jewish girl who knows nothing about subterfuge, all she has going for her is her absolute determination.
I should mention that this book is the third in the series, and since each follows right after the previous one, you'll be familiar with a lot of the characters and enjoy it more if you read them in order. Not all of the main characters are Jewish, but the series loosely revolves around the Meyer and Roth families who are highly involved in espionage and secret courier services on behalf of the British. A little background knowledge, like knowing the difference between Sephardic(aka Spanish) Jews and Ashkenazi Jews(aka Tudesco in this book) also helps. But you can pick up most of the information, like the legal restrictions that existed on Jewish people in the 19th century, as you go along.
There are also subplots involving an orphaned girl they pick up along the way, a family of smugglers, a royalist plot to overthrow Napoleon, James's father who is a master spy, and oh, all sorts of stuff. Just go read it!