In this Captain Lacey book, we learn more about Colonel Brandon and the time period where he wanted to annul his marriage to his wife, Louisa, who hasn't able to bear Brandon children. We get there by way of the murder of Mr. Turner at a Season ball, for which Brandon is arrested. At this particular ball, Brandon made a real cake of himself with a Mrs. Imogen Harper, the widow of an officer who served in the Pennisular Wars with Brandon and Lacey. And, a woman who had an affair with Brandon shortly after her husband's death -- Brandon's plans to annul his marriage to Louisa had to do with his deciding to take up full time with Mrs. Harper in hopes of stocking his (Brandon's) nursery with heirs.At this ball, Mr. Turner is obviously being obnoxious towards Mrs. Harper, which seems odd, since Mr. Turner is a young buck of an age with Leland Derwent and pals. Brandon can't seem to help but get between Mrs. Harper and Mr. Turner at every turn. So when Mr. Turner is found dead in a side room with Brandon's knife in his heart... and Grenville witnesses Mrs. Harper screaming over Turner's body, blood on her glove... it becomes the on dit of the Season. Brandon stubbornly refuses to answer questions and is summarily thrown into Newgate to await trial. He angrily tells Lacey to leave it alone. But we know that Lacey cannot. If for no other reason, Lacey's loyalty to Louisa compels him to discover the truth. Besides, Lacey doesn't believe that Brandon murdered Turner in such a sloppy fashion as to leave his own knife behind.Brandon confesses to an affair with Mrs. Harper, who confirms that the affair took place. Lacey realizes that Turner was blackmailing Brandon and Mrs. Harper. Lacey locates 3 recent letters from Mrs. Harper to Brandon that hint of the affair, but also point to some mysterious dealings between them that could take both Brandon and Mrs. Harper down. While Lacey is trying to decipher what those dealings might be beyond the scandal of their affair, an unknown Frenchman - obviously an officer - attacks Lacey and makes off with the letters. Lacey no longer believes that the blackmail is only about an affair, for why would a French officer be involved? And somehow involved with James Denis, who also wants whatever Mrs. Harper and the French officer are looking for.Brandon won't talk to anyone, not even his wife Louisa. He stubbornly insists that Lacey leave it alone and take the spoils of his wife. Lacey realizes that Brandon's jealousy all of these years over his relationship with Louisa goes much deeper than just thinking that Lacey took Louisa's side over his. As we all have realized without the proof up to this point, Brandon's jealousy stems from his own indiscretion and affair, thus he believes that the loyalty and love between Lacey and Louisa can only mean that they've had an affair, too.Louisa is beside herself. At one point, she throws herself at Lacey, begging him to take her France and away from all of this horror. She tries to tempt him by telling him they can look for Lacey's wife and his daughter, who Denis has told him are near Lyon, France. If Lacey wasn't romantically involved with Lady Breckenridge, he probably would have flung himself head-long into an affair with Louisa and done just as she asked, leaving Brandon to swing for a murder he didn't commit. But because Lacey is in love with Lady B, he's wise enough to see that his love for Louisa is beyond a romantic liaison that they would both come to regret in time and that would likely snuff out any love and friendship between them.So Lacey pursues the trail with Grenville, Bartholomew, Matthias, Pomeroy and his Bow Street Runners, and even the Derwents. It's a twisted trail of the young Mr. Turner, who, despite careful appearances is not only an "unnatural", but also a master blackmailer. The French officer was an obsession with Mr. Turner, and when he couldn't have him, Turner took some papers from the French officer -- dangerous papers that point to treason and intrigue that involve Mrs. Harper's husband, the French officer, and even Mrs. Harper and Brandon. Can Lacey find the real killer in time to keep Brandon from swinging?--------------I liked this book a lot, because Brandon has been such a beast, it was nice to see Lacey put him in his place. Because as much as Lacey has hated Brandon for all that he did to Louisa and then to him (Lacey), Lacey has true honor and nobility. He's given the chance to rub Brandon's face in his past sins -- sins that caused Brandon to try to abandon Louisa, which led to Brandon sending Lacey off to be killed; instead, Lacey survived the mission, but lost the use of his left knee after being tortured. Lacey could let Brandon swing and run off with Louisa. But he doesn't. And know Brandon is indebted to Lacey, which has to anger him that much more. Poor Louisa! She must truly be a strong woman to survive this, although at the end, we're unsure where she stands. She seems to stand by Brandon, although will they remain together? And now she's embarrassed at throwing herself at Lacey, so she's not talking to him or seeing him... and yet, we get the feeling that this is temporary.Thank heavens for Grenville! Although the drama with Marianne is a bit much... Although we do have a bit more revelation about Grenville's life, as it concerns a young actress. Is she Marianne's rival or something else? (And that glimpse is very small, and IMO, not done well; we don't have much to go on until Grenville, himself, tells us the truth, and that's not very sporting of the author.)Lady B! So glad that she's not quite the "proper" widow, and that her affection for Lacey and his for her is not only mutual, but growing. There's a chance for happiness for Lacey yet!The book is somewhat esoteric at times... the convoluted motives of the murderer are almost completely hidden, yet we suspect whodunnit early on. Is the author trying to be too clever and leave the reader out of the solution? Hmmm... I can forgive some of that, because Lacey makes the right decisions and truly has a chance for happiness in future books.