A copy was provided by the publisher through Netgalley in exchange for an honest review 
 I do not recommend this book to trans, non-binary, and/or disabled readers. 
 I was really excited for this book. Genderfluid character in a historical queer romance by one of my favorite authors...I was anticipating this book for months. Unfortunately, the genderfluid representation--which was what I was so excited for--didn't work for me. And I was also troubled by the disability representation. 
 This has all the hallmarks of a KJ Charles romance, with all the skill I would expect: the language is beautiful, it's deeply characterized, very well paced. It has all that I would expect from this series in terms of tension and mystery and resolution. There is no question that Charles has tremendous writing chops, and this book shows it as much as any of her other books have. The series builds through the books, and this one really should not be read alone, it would be much more satisfying and also make more sense if you read the first two books in the series (which are very good and well worth reading, by the way). 
 Note: I am going to use the pronoun they to refer to Pen, though the book uses he. Pen explains that using he is easier but doesn't feel right, and that there are no other options. I don't know what pronoun Pen might choose today, but I doubt that it would be he, so I am going with they. Which doesn't mean that non-binary folks don't use he or she (when I was genderfluid I used she), but more that I don't think Pen would. 
 The biggest issue I had with the genderfluid representation was that the entire plot hinged on this imminent threat to force Pen to stop expressing their genderfluidity and conform to a binary gender. Up til nearly the end the reader (and Pen) don't know if that is going to be what the rest of Pen's life is going to be like, or if there is a way out of it, a way for Pen to be themself. As a non-binary trans reader who spent ten years of my life being genderfluid, who was often pressured to conform to a binary gender, and for whom that pressure was extremely destructive and harmful, reading a book with this plot structure felt like reading a horror story. It was incredibly difficult to read. In fact, I put it down for about six weeks and wasn't sure I could pick it up and actually finish it. 
 Throughout the novel, I kept thinking about how it doesn't have to be this way. How the genderfluid character in a historical romance doesn't have to be set up to be forced to mask their gender like this. This was a choice, and there are many other choices out there. Unfortunately, this is a common cissexist trope in stories about trans and non-binary characters, that they are forced/coerced to detransition or conform to a gender that they aren't. In fact, I started another ARC with a non-binary character in the same week I started this one, that also had this trope. 
 The resolution of the threat doesn't really make a difference for my reading experience, so I'm not going to talk about it, or spoil it for you. I was terrified for Pen the entire way through, and even if the book were to remove the threat at the end, that reading experience stays. This genderfluid character is terrified (and I was terrified for them as a reader) that they will be forced to conform to a binary gender throughout most of the book, the thought of it causes intense dysphoria, and the threat of it only worsens their dysphoria and causes them incredible pain. This character has had their genderfluidity and the threat to it used as a central plot device in the story, the thing that creates conflict, the thing that is used for tension, the thing that creates obstacles for the lovers. 
 I could not forgive Mark for his actions, both in minimizing Pen's feelings about the threat and in putting Pen in the line of fire. I wasn't rooting for the lovers, I thought Pen deserved much better than someone who would do that, and did not feel that Mark earned Pen's forgiveness for it. This was exacerbated by the fact that it's very clearly stated by Pen that they think Mark is a miracle just because he sees and understands Pen's gender as much as he does. That Pen never thought it was possible to find someone who got it and accepted it, and Mark is wonderful and rare just because he is a cis lover who does. I have written quite a bit about this cissexist framework and the internalization of the cis gaze in this essay: http://xanwest.wordpress.com/2017/03/.... It hurts to read stories that do this, that frame cis people as rare and miraculous just because they get and accept non-binary or trans people's genders. When Pen said this, it was like a kick to my stomach. And it never gets challenged in the story, its presented as simply the truth. 
 I also had substantial issues with the sex scenes. They definitely weren't hot in the way that most of the sex scenes in Charles' work usually are. They felt deeply othering, and like they were very much about Mark attempting to figure out how to have sex with Pen and respect their gender, and almost everything else disappeared. They felt simultaneously like they treated Pen's gender as a problem to solve and a thing to fetishize. It also felt like it invited the reader to fetishize and other Pen, and to think of the sex they were having as weird workarounds because of Pen's gender. I was tremendously uncomfortable reading the sex scenes, both because of this, and because of the way Mark's disability was represented. 
 Marks disability was framed in a similarly othering manner, that was part of the sex scenes, but also in general. Pen approaches Mark's disability from a deeply othering place, mentioning several times that it makes him queasy to think about it, constantly being surprised that Mark can be independent and do things on his own, and frequently trying to "understand" in a way that felt creepy and objectifying to me. This translated to some of the moments in the sex scenes that are from Pen's POV (which are rather rare), including a scene I had a particularly hard time with where Pen touches Mark's stump and is fascinated by how it feels. This is both a common trope esp with disabilities that are perceived as disfiguring, and also just felt so othering. This ableism was hurtful to read, and was one of the things that made me consider not finishing the book. 
 There are a couple notable scenes where the MCs compare being non-binary to being disabled, and these scenes felt deeply problematic, and generally made me very uncomfortable, as a disabled non-binary reader. The first time I read the first scene where this occurs (there are two main ones, this one is about 33%), I put the book down, and didn't pick it up for 6 weeks. I stopped reading again the second time, again unsure if I could make it through a book with this kind of representation. I picked it up again the next day, and pushed through it, but it was very hard, and these kinds of comparisons being offered and never challenged were definitely one of the reasons. 
 Unfortunately, the issues with the genderfluid representation and the disability representation ruined the book for me. I didn't find it enjoyable at all as a story, and did not want the lovers to end up together. 
 Note: If you are looking for other books that I would recommend, with non-binary characters, I did a recommendation list recently: https://justlovereviews.com/2017/07/2... 
 Trigger Warnings: (view spoiler)[ So much misgendering. Lots of coercion and pressure and threats of force to conform to a binary gender. Murder. Attempted murder. Torture. MC in peril of violence, torture and murder for the entirety of the book. Hostage situation, held at gunpoint. Queer hatred and cissexism including repeated use of slurs and threats of violence and being outed. On the page sex. (hide spoiler)]