Exodus (The Ravenhood Trilogy #2) by Kate Stewart

I did what thieves do. I stole you... What Cecilia Horner had expected to be a dull year has already been the most exciting summer of her life after she met local bad boys Sean and Dominic and their relationship developed into something altogether more dangerous. But she is left reeling from the discovery that they are members of The Ravenhood, a secret group of vigilantes. At the head of the society is a man known as the Frenchman and he doesn't want Cecilia anywhere near his men or his mission. She has every reason to hate him but there's a fine line between love and hate. And if her time in Triple Falls has taught her anything, it's one she's more than willing to cross