I tend to react to certain characters or plot devices with my gut rather than my head; they appeal to me, and only afterwards do I realize how many holes there were. I experienced the opposite with Caroline Linden’s latest entry in her historical spy series in that my initial gut reaction was positive but tepid. However, as I wrote the review my head started jumping up and down, and in retrospect I realized that in its own quiet way, You Only Love One is a very good book.

Angelique Martand, a French-born English spy, is having a crisis. She’s tired of being alone, tired of being an assassin, and she’s not sure her boss is sending her out for ethical reasons any more. So she promises herself she’ll finish one last job before kicking it in. Unfortunately, her assignment stinks to high heaven.

She is ordered to work with Nate Avery, an American sent to London to retrieve an embezzler named Dixon. She and Nate will pose as husband and wife to fish out Dixon’s hiding place. But there are complications. First of all, her employer tells her to assassinate Dixon, without providing a reason or informing Nate, who wants to bring Dixon to justice in America. And second of all, Angelique and Nate are falling seriously in love with each other, but how will Nate react when he finds out she’s little more than a hired blade?

The book begins a touch groggily, but when the chemistry kicks in the story goes into full throttle. Angelique and Nate are crazy hot together (whoa, are they ever), and what makes their romance even more attractive is the unusual characterization. Angelique, for instance, could easily have been another deceptively sensual spy who finally gives up her virginity to her partner while screwing up royally, but it’s not like that. She’s not a virgin, and she’s not stupid; instead, she is smart, capable, mature, and matter-of-fact about her vocation, realistic without being overly melodramatic. Nate is a refreshing change from the usual run of tall strapping heroes, being of rather middling height and nondescript features. Although he appears rather bland at first, his strengths shine through once Angelique and the reader get to know him. Their romance could have been theatrical and a bit over the top, but it was passionate and gripping instead.

The balance is a large part of the book’s charm. The plot develops at a good pace alongside the characters; Ms. Linden takes the time to weave a logical plot and answer all the questions, without being tiresome or heavy-handed, and the twists are interesting but not ridiculous.

Although I didn’t love it, the more I think about it, the more I appreciate You Only Love Once. It’s plausible, and Ms. Linden tells a story effectively and gracefully.