Grey Summers, Lord Wyndam, has been stuck in gaol somewhere in France for nearly a decade for the singular offence of dallying with a married woman whilst spying for England. Oops. Fellow spy Cassie Fox (obviously, not her real name) is sent to spring him from his hellhole.
No Longer a Gentleman is the fourth book in the Lost Lords series by Mary Jo Putney. Although I hadn't read the other three books, this one was fairly easy to follow (except the whole school/Hindu fighting style thing, that took a bit to figure out - Kirkland's spy network was not).
The plot had a very Count of Monte Cristo vibe with the "10 years in a cell with a priest to keep you company" plot device right down to Gray's penchant for revenge (although not as elaborate). Cassie was an interesting heroine and it was nice to see Putney attempt to work in some of the grittier aspects of the reality being an orphaned English girl during the French Revolution. OK, well, it wasn't "nice" but it grounded the narrative in a unique way.
The serious complaint is that it's too predictable, even for a romance novel. You know that Cassie will get Gray out of his hellhole, that they'll fall into lust then love, that Gray's family will accept him back without reservations, that Cassie will (in a plot move worthy of Dickens) be find her long-lost relatives, and that Cassie and Gray will wind up having to go back to France for the denoument of the novel. That last bit would have gone better if the reader hadn't been given the villain's point-of-view - that was unnecessary. The novel was enjoyable, but I don't know if I'll go back and read the first three.