This is book 3 in an ongoing series. While it can be read as a stand alone, the world building and the overarching story line will make a lot more sense if you start at the beginning, with Kiss of Steel.
Sir Jasper Lynch is the head of the Nighthawks, basically the mostly nocturnal police force of the Steampunk London that Bec McMaster has invented here. All of the nearly four hundred Nighthawks are rogue bluebloods, people who have caught the craving virus by accident in some way (become vampires) and who are not of the Echelon, the nobility who rule the country. After an assassination attempt on the Prince Regent, Lynch is tasked with finding the notorious human revolutionary, Mercury. If Mercury is not brought to justice within a short space of time, Lynch’s life is forfeit instead.
Using his enhanced senses and his decades of experience with detective work, Lynch manages to track down Mercury, and is shocked to discover that the revolutionary is a woman. Not only that, she manages to get the better of him by using her feminine wiles to distract him, then she escapes. Now the reason he wants to find her is as much professional as it’s personal. Little does he realise that she’s much closer than he is expecting.
Rosalind Fairchild needs to find her missing brother, who was involved with the rogue group of revolutionaries who tried to blow up a large part of the Echelon and visiting dignitaries from Scandinavia. She needs to infiltrate the Nighthawks, and gets herself hired as Sir Jasper Lynch’s personal secretary. She knows that if he discovers that she is also Mercury, he will arrest her and hand her to the Echelon to be executed, but Rosalind has been trained for subterfuge by the very best, and has no intention of getting caught. She needs to locate her brother, rescue him and then she can go back to ridding the world of all bluebloods.
More on my blog.