I adored this book. Everything about it was just chef's kiss. I loved the language, the pacing, the plot, the dialogues, the interactions between the characters and the intricacy of their relationships. The subtle humour at times, and the overall darkness were both so well done.
This is not a book for the faint of heart. It has some very dark themes and the characters are an assassin in training who had watched her parents get murdered in front of her as a child (like batman) and the assassin who trains her who has his own crosses to bear, though very little of that is revealed in this. Murder Batman as the book is called by the author, is certainly a fitting moniker.
Cerise is an orphan who was brought up by her aunt, a madam of a brothel. When she was of age, her aunt throws her out since she can't afford to keep someone who isn't earning her keep. To add to it, Cerise is half Mostrian and looks it and is subject to bigoted and racist comments from the Lieurenese people she lives among. Not to speak of the fact that she's bisexual and growing up in a brothel has no qualms about seeking lovers, and her acceptance in society is even trickier.
Enter Keir, the charming assassin who wants to train Cerise because she's a shadowwalker like him, a mage who can manipulate shadows and turn to shadow themselves. He's part of an emperor sanctioned assassin's guild called the Red Society and wants to recruit Cerise after he has seen her use her powers to kill a man who attempts to assault her. Cerise, out in the streets with no one to turn to and no way of getting a job due to her Mostrian nationality, is only too glad to turn her skills from petty thieving and murder to something that actually gets her a roof over her head and three meals a day. Or more. Depending on the day.
Keir has his own motives in training Cerise, but even though he's secretive, he's also vulnerable and charismatic. They fall for each other like a ton of bricks, but dance around it due to Cerise's fear that she's only going to drag Keir down and his realisation of her fears. Cerise is also having feelings for Keir's best friend, Damara, who is a noblewoman, and though Damara reciprocates Cerise's feelings, their being together is not an accepted thing in their society especially with Damara's status.
Add in an arsonist targeting brothels including that of Cerise's aunt's, a deadly fever that has Cerise lose access to her magic, and the mysterious fate of Keir's last apprentice, the stage is set for a plot that has so many twists and turns it leaves you breathless. It slows down at times to let you catch a break before taking you along for the ride again at breakneck speeds.
This is an extremely well crafted and well written books with very real, relatable characters. They're all very flawed, but very very human.
If you love gaslamp fantasies, victorian seeming settings, disaster bis pining for each other, mysteries and lots of magic and spice, this is exactly the book for you.