So much to love about this book... a few nits, but overall, I was drawn in to the characters and the story.However, if you're considering reading this book, something that isn't made perfectly clear is important to your understanding and enjoyment of it. Ian is "mad", and we know that he's not really mad, but he's definitely odd. If you go no further than that, a lot of his actions seem harsh and cruel and... mad. I wish the author had been more specific (even in Author's Notes) that Ian has some form of autism - possibly Asperger's syndrome. His form of autism enables him to function at a very high level, close enough to "normal" behavior that one can see how Ian would be thought simply in need of treatment. If you keep this in mind as you read the story, Ian's actions take on an entirely different meaning, especially his rages and his inability to make direct eye contact. You can see his mind working... grasping to be "normal". His ideas about love and emotions make so much more sense. And you discover that Ian is not only unique, but a truly loveable and likeable man.And discovering more about Ian's life and what happened to him - why he was put into the sanitarium - brings things into stark reality. You see how strong Ian is to have survived so much in his life. You see how he truly does have emotions - he loves his brothers and he feels loyalty towards friends. While the title (Duke) brings them much riches (2nd richest in England behind royalty), the Mackenzie's lives have been anything but easy. This isn't your mother's Regency or Victorian romance. It's not all lightness and wit and silly intrigues and gossip here.Beth is a widow with a rough past, herself. Her father claimed to be a French Viscount, but he was really an alcoholic con artist. When her mother, an English lady, married her father, she was disowned. So when all their money and her father was gone, Beth and her mother were thrown into the workhouse. Beth survived and was able to find a way off the streets and didn't have to sell her body to survive. She met and married a tenderhearted vicar, Thomas, who worked in the mean streets of London and cared for the people there. Thomas taught her about love and making love (not just sex). He taught Beth that there should be a good, enjoyable intimate relationship between man and wife. But Thomas died within a year, and Beth found herself once more at the mercy of others; she became a companion to a rich widow of the Ton. That widow was all involved in the fripperies of Society, and so she introduced Beth to that Society, although keeping Beth on its fringes. When the rich widow died, for some reason she gave all her money and house to Beth - probably one of the only good things she did in all her life. Oh, the rich widow was harmless, but not necessarily a good person.When the story starts, Beth is engaged to marry Sir Lyndon Mather, related to the fussy rich widow. Mather is a secret rakehell and deeply in debt. In fact, Mather has a house where he employs several "ladies" who serve his fetishes and those of his friends; apparently, Mather likes to be punished like a schoolboy. So when Mather jokes about his intended and how he will keep his naughty ways, Lord Ian is appalled and intrigued. Ian wants to know if Mather's intended (Beth) is real or fake - fake like Mather or real and worthy of someone better than Mather. Lord Ian collects Ming bowls, and so does Mather; except Ian knows how to distinguish fake from real and determine the true worth of the bowls. Mather hasn't the faintest idea that many bowls in his collection are fake.When Lord Ian finds out that Beth is real and worthy, he warns her away from Mather and offers her marriage to him. Ian is instantly drawn to Beth: she is gentle with him and calms him. And while she doesn't quite understand his strange ways, she's drawn to him, too. Both think it's only a physical connection - Ian especially, since he decides he wants to bed her immediately. And the only way to do that with a worthy lady is to marry her. Ian warns Beth that he doesn't feel love and doesn't know how to give it; but he won't expect love from her, either. Beth doesn't know what to do with this, but she does decide to call it off with Mather, torpedoing Mather's plan to get his hands on Beth's money.Beth decides to enjoy her freedom and travels to France, where she meets one of Ian's brothers, "Mac" - a painter and separated from his wife, Isabella. Mac is in France to paint, but also to be near Isabella. It seems they can't live together and can't quite stay apart. Lord Ian follows Beth to France, determined to make her his. But Ian is followed by Inspector Fellows, a man who's made it his life's work to hound the Mackenzie boys. Fellows was part of an investigation 5 years ago in which Ian and his oldest brother (Hart) the Duke were involved -- the stabbing of a prostitute, Sally, in a house that Hart had previously set up his mistress in. (The mistress is now the "madam" of the house.) Fellows is convinced that Ian killed Sally, and that Hart and the family are covering it up. And just before Ian left London, he discovered the body of Lily, a prostitute from the house who knew Sally; Ian had been hiding Lily, concerned that whoever killed Sally would kill Lily. And it seems as if the killer did return, because Lily was stabbed with her own scissors. And Ian was seen leaving the house. Fellows is determined to nail Ian for both murders this time. And Fellows even hounds Beth, warning her away from the Mackenzies, spilling their secrets, and -- surprisingly enough, makes an offer for her hand!In a whirlwind of events, Beth decides to take Ian on as a lover... Ian and Beth end up getting married after being chased out of an illegal gaming den by Fellows... and we finally meet all of the Mackenzie men. And are given hints about the other mysteries in their lives, mostly about women. Beth has fallen in love with Ian, and she wants to solve the mysteries of Sally's and Lily's deaths once and for all. Beth is convinced that Ian had nothing to do with the deaths, and she knows they haunt him to distraction; Beth wants to remove all of that from her husband forever, even if she has to join forces with Fellows to do it.-------------LOVELY book! Yes, it's quite steamy! Which is why readers must understand that Ian has some form of autism, because he quite readily thinks and says exactly what's on his mind, especially about sex. And Ian not only enjoys sex, he's quite skilled at it, teaching Beth a thing or two! Yes, men might think that way often, but it's unusual for an author to write a character's thoughts exactly as they are; and it's for a reason -- to help us see and understand Ian. But if you're not into that kind of steam, this probably isn't the book for you. Because as soon as Ian meets Beth (in the first few pages of the book), he's thinking exactly what he wants to do to her and how.I really loved the way that Beth accepted Ian, without question. She doesn't try to make him to be anyone else or try to get him to "behave" according to Society's standards. Beth empathizes with Ian as another person on the fringes of Society, but not quite fully accepted - as she is. Her upbringing and her 1st husband all bring her experience and wisdom on how to gently love and calm Ian without treating him as an imbecile or try to over-protect him. And while Ian doesn't recognize the depth of his emotion for Beth - he doesn't know what love is or how it feels - he's constantly asking Beth to describe emotions for him, so that he can see them through her eyes.Yes, the playing detective bit might seem to some as a story device and unnecessary, but in context, it makes perfect sense. Beth pursues the mystery to free Ian from his torment, because she LOVES him. Her purpose is all about Ian.The author has set up a very interesting family of characters, not only Ian and Beth, but the Duke (Hart), Cameron (Cam), Cam's teenaged son Daniel, "Mac" the painter brother, Isabella Mac's estranged wife, Katie Beth's outspoken maid, and the various valets that each brother has employed from the streets. I'm looking forward to reading the next book in the series.