The Mask of Mirrors (Rook and Rose #1) by M. A. Carrick

Darkly magical and beautifully imagined, The Mask of Mirrors is the unmissable start to the Rook & Rose trilogy, a rich and dazzling fantasy adventure in which a con artist, a vigilante, and a crime lord must unite to save their city.

Nightmares are creeping through the city of dreams . . .

Renata Virdaux is a con artist who has come to the sparkling city of Nadezra -- the city of dreams -- with one goal: to trick her way into a noble house and secure her fortune and her sister's future.

But as she's drawn into the aristocratic world of House Traementis, she realises her masquerade is just one of many surrounding her. And as corrupted magic begins to weave its way through Nadezra, the poisonous feuds of its aristocrats and the shadowy dangers of its impoverished underbelly become tangled -- with Ren at their heart.