This is the fifth and final book in the London Steampunk series. There will be minor spoilers for previous books in the series, and it's really not the best place to start. If you're interested, start at the beginning with Kiss of Steel.
The precarious power balance in the capital is becoming untenable. Human Queen Alexandra is more of a powerless puppet to her powerful and erratic blueblood (vampire) husband, the Prince Consort, than ever before. Even the ruling council of the Echelon (the nobility) have little control over his more and more unpredictable decisions. The common people, normal humans and mechs (humans who have had limbs replaced with mechanical prosthetics after accidents) are being pressed harder than ever before, with more extreme blood taxes and the situation is reaching a breaking point.
A number of people are working quietly to fortify Whitechapel, controlled by Sir Henry Rachinger, better known as Blade or the Devil of Whitechapel. Since his wife, Honoria, published the scientific findings of her dead father, leading to a vaccine against the blueblood virus, the Prince Consort's power over the Echelon has slipped further. The heads of the city's police force, the humanist party, Blade, his wervulfen sister- and brother-in law, as well as the heir to the Duke of Caine, Leo Barrons are all working together to fortify the walls of Whitechapel and get enough ammunition to incite a proper rebellion.
Unbeknownst to them, Lady Aramina or Mina, Duchess of Cassavian and one of the few blueblood women in London society, has been working diligently for nearly a decade, funding the humanists. The queen is her best friend and she hates seeing how the Prince Consort abuses and manipulates her. On the surface, she's all coldly correct, supportive of the Prince Consort's rule, even willing to help him physically reprimand his wife. Behind closed doors, she works tirelessly to keep the queen's spirits up, spending as much of her private funds as she can to arm the humanists. She has no idea that there are others working towards the same goal, including the man she considers her enemy.
Mina believes that the Duke of Caine killed her father and has sworn revenge against him and his son. She doesn't know that Leo isn't actually the duke's son, that he has three half-siblings, including Honoria, Blade's wife. While she wants to hate him, Leo on the other hand, is fascinated by Mina and wants to crack through her icy veneer to unleash the fiery, passionate woman he believes she is hiding. Unfortunately, when the Prince Consort gets access to the truth of Leo's parentage, through a duplicitous investigator Mina hired, he is forced to go into hiding. Believing Mina to be the one who betrayed him, he takes her hostage, dragging her into Whitechapel, the only place he can hide. When he runs, the Prince Consort declares he will burn the area to the ground. The plans for rebellion need to be put into action.
While I thought the first two books in the series were a bit slow, the last three were extremely entertaining and it was especially refreshing to see that the cold and frankly quite snooty-seeming Duchess of Cassavian not only had hidden depths, but was a full-fledged badass. On his deathbed, her father defied tradition and infected her with the craving virus and she was forced to kill any pretender to her title in order to protect herself. Having lost her older brother before the Duke died from mysterious causes, with her mother becoming catatonic with grief, Mina has lived a very lonely and dangerous life. She can't openly support and champion her only friend, having to work behind the scenes to remove the tyrannical Prince Consort. Because society believes that women are too weak and emotional to handle the craving virus, she has to work twice as hard as the Echelon males to stay in control of her bloodlust and urges, to prove them all wrong. She's had lovers, but is afraid to let herself go completely and therefore feels both tempted and frustrated by Leo's advances and refusal to give up courting her.
Leo is also very lonely, having been raised in an almost militaristic fashion by the Duke of Caine, who was treated the same way by his father. Having realised early on that he was illegitimate, Leo still feels guilty about refusing to help his half-siblings when they were in need, resulting in Honoria's bargain with Blade, which in turn led to her marriage. Leo became infected with the craving virus because of a botched experiment of his biological father, and as revenge doctored the vaccine Sir Artemus Todd was planning on taking, not realising that he also meant to give it to his son Charlie, Leo's half brother. Charlie became a rogue blueblood, and Leo has never been able to forgive himself for causing this. Even after his half-siblings have forgiven him and try to include him as much as they can, they can't openly show their connection. Once the Prince Consort discovers the truth for himself, and orders Leo executed, his sister and brother-in-law are the only ones he can turn to for help.
Mina is appalled that the man she paid to investigate Leo also reported to the Prince Consort. Being held prisoner by Leo and Blade in Whitechapel when the city is about to erupt in civil war is disastrous for her, though, as she needs to make sure the queen is safe. This leads to her trying her best to escape, while Leo keeps chasing her down, becoming more and more aware how important she is to him.
The romance in this was excellent and I was impressed with how well McMaster united all the various pieces that she's introduced in the previous books. With every book, she's introduced one more thread, bringing them all together here. Discovering that Mina was the financial source behind the humanists was a delightful surprise, and when she finally allows herself to give into her attraction to Leo, things get pretty smoking hot. With some Steampunk series, that element gets unnecessarily gimmicky, not so here. The world-building and character development has been excellent throughout, and it's always good to see a series that ends on a high note instead of fizzling out. I highly recommend McMaster's books to anyone who likes paranormal historicals and look forward to what she's going to write next.