A few hundred years before the novel opens, the Asian Horde took over much of the Western world with a mix of force and superior technology. Lacking any navy of merit, they had to be a bit creative in their attack on Britain, choosing to smuggle nanoagents into the cheap sugar and tea they exported to the island nation. As the people ate and drank, they unwittingly infected themselves with tiny bits of self-replicating machinery. While the "bugs" made people stronger, hastened healing and allowed a wide range of prosthetic enhancements, the downside was that the Horde could control the infected via a radio frequency transmitted by a tall tower in London.The story takes place nine years after Rhys Trahaearn, now known as the Iron Duke, blows up the tower, freeing all of Britain from Horde control. After a bloody revolution where a mad populace attacked the Horde and each other in a fury borne of a lifetime of tight control suddenly ended, Britain is at a crossroads. The descendants of the wealthy Brits who fled England before they were infected have returned, creating tension between the infected "buggers" and the uninfected "bounders" as to who has more right to Britain. Does it belong to the people who spent the past few hundred years hiding out in Manhattan City in the New World, or to those who endured and overcame Horde rule, but will always be susceptible to control because of their bugs?In the midst of this heady drama, a body literally lands on the Iron Duke's front steps and Detective Inspector Mina Wentworth is called in to investigate. Born after a "Frenzy," where a Horde signal causes all buggers to copulate with each other, she's the half-breed daughter of a English countess and a Horde member who was at the state dinner her mother was attending. Though her parents are noble and she's a distinguished member of the Metropolitan Police force, she encounters constant abuse due to her Asian features. As a result, she's a bit like Eve Dallas - a big squishy ball of insecurities well hidden under a granite facade. Through the love of her supportive family and a singular dedication to her work, she gets by in a world she feels completely apart from.Working on the mystery of the body tossed onto the Iron Duke's steps tests her resolve. As a former pirate, Rhys is accustomed to taking whatever it is her desires, and he decides that Mina will be his latest acquisition. As they fly and sail around England, Europe and Africa unraveling the murder mystery and uncovering a doomsday plot that endangers all the buggers in Britain, the two also are working to figure each other out. Rhys is determined to have her, and Mina is determined to resist him, lest everything she or her family has worked for go up in smoke in the subsequent mockery of the Iron Duke taking up with a "Jade whore."The world-building was superbly done, creating a full, complex world and divulging it at a natural pace throughout the book. All of the secondary characters were fully-fleshed out, providing bits of humor, drama, action and everything in-between when the plot required it but without feeling convenient. The action keeps a steady, energetic pace throughout the book, making it a hard book to put down at times. Brook has created a stunning steampunk setting that's creative and expansive while remaining entirely accessible. There are easily drawn parallels to our own world and the messy politics of today without anything being obvious, sanctimonious or preachy. It's complex enough a world to let you forge your own theories of what is afoot, and approachable enough that you'd want to do so.While I loved the steampunk aspects quite a bit, the romance didn't move me. There was just something about the romance that left me kinda cold. I almost resented the breaks in the action plot and half-skimmed the sex. Their emotions towards each other felt a bit forced, so I felt like a voyeur watching them together. The sex didn't seem to be resolving a tension between them - anguish over memories of a past Frenzy notwithstanding - and so it felt gratuitous.Part of the issue might have been that I didn't feel I really knew Rhys or Mina. I loved them as catalysts for the action - Rhys the alpha, protecting what he considers his and Mina the fighter, always trying to forge order from chaos - but didn't get a good feel for them as humans. I was told that Rhys "respected the hell out of" Mina, but I was never really shown why. What made her so special to him? What about Rhys tempted Mina? I needed to see more talking, vulnerability and emotional intimacy between them. As it was, I was told they were hot for each other, and I watched them bone, and that was the romance.As a romance, it lacks a certain something. As a straight sci-fi, I think I'd have loved this book unreservedly. The world she's created and the secondary characters she populated it with are absolutely spellbinding. For all its faults, it was still a hard book to put down. I'm certainly itching to read the sequel a year from now.