The Vows We Keep by Scarlett Cole

Catalina
As the daughter of a Los Reyes motorcycle club vice president and an assassin, I understand the risks of this life.
Yet the club won’t tell me why my father went on a ride to New Jersey and never came home.
So the Iron Outlaw I just kidnapped and tied to a chair is going to tell me instead.
Except nothing I do to this man scares him. His strength and courage match my own.
But this is a battle only one of us can win.

Niro
Catalina wants answers I can’t give her, but I’m intrigued by this woman.
Because I buried every Los Reyes club member that day, and her father wasn’t one of them.
I need to stay alive long enough for my club to find me.
But the more time I spend with Catalina, the more I want to help this leather-clad assassin who challenges my view that I’m better off alone.
Even if helping her keep her vows of revenge could kill us both.