House of Bane and Blood (Vows of Vengeance Duet, 1) by Alexis L. Menard

Set in a post-industrial age magical Isle, Peaky Blinders meets Shadow & Bone's Grishaverse in this fantasy romance where a contract marriage brings two enemies together but threatens to burn their city to the ground. In a city split into two opposing sides, power comes in many forms: bloodlines, money, love, and—most importantly—secrets. Camilla Marchese is fighting a losing battle to keep her family’s syndicate from slipping into bankruptcy. So when the gorgeous and merciless Nicolai Attano, leader of a rival family, offers to pay their debt in exchange for her hand, she has no choice but to accept. For Nicolai, the marriage is essential to prevent a war, especially as a serial kidnapper known as The Collector has been ravaging the streets, stirring up mistrust between their opposing sides of the city. If Milla can help Nico find The Collector, she can walk away from their union with more freedom than she’s ever known. But this deal plunges them into a deadly game of depravity between remnant magic and arcane science. As the two grow closer and the stakes grow ever higher, will they be able to trust each other enough to discover the truth before it gets them both killed or worse—collected. Read more