Vow of Loyalty by Bonnie Poirier

She’s spent two years being invisible.
A rumor. A shadow moving through a world that doesn’t know her name or what she’s capable of. Emilia runs her family from the dark, pulling strings while her father sits on a throne he doesn’t know she’s taken from him, and she’s never once looked over her shoulder.

Until the night Niccolo Venosa’s SUV idles outside her massacre.
He’s the most dangerous man in Chicago. The man who controls it all. Ruthless, and impossible to read, and now he knows exactly who she is and what she’s done.

Emilia’s father trades her like a bargaining chip, she tells herself it’s just another power play. She’s navigated worse. She knows how this world works, knows how men like Nico operate, and she has no intention of becoming anyone’s prize.
But Nico doesn’t want a compliant wife he can manage from a distance. He wants the woman behind the shadows, the one with blood on her hands and a mind sharp enough to match his own.

And the terrifying part isn’t that he sees exactly what she is.
It’s that he’s the first person in this world who’s ever looked at her like it’s everything he needs.