Estep, Jennifer. Black blade novel.

As a thief, I'm good at three things: hiding in the shadows, getting in and out unseen, and uncovering secrets. I put these skills to work for the Sinclair Family, one of the magical mobs that run the tourist town of Cloudburst Falls. Everyone knows Victor Draconi wants to take over all the other Families--and kill every last Sinclair. What they don't know is that I'm on to him, and no way will I let the man who murdered my mom get away with hurting all the other people I care about. Especially when I've got places to break into, stuff to steal, and Devon Sinclair fighting right by my side&