Female of the species

Alex Craft has killed a man – and she doesn’t regret it. When her older sister Anna was murdered three years ago, the police failed her. The killer remained at large and it seemed he would never face justice. That's when Alex first unleashed the darkness dormant within her and killed him. He was the first, but he certainly wouldn't be the last.
You see, Alex isn't like other people. She’s a ticking time bomb, a cannon with a lit fuse. She is a danger to everyone around her. To Peekay, the local priest’s daughter, whom she befriended at the dog shelter. To Jack, a promising athlete who would like to get to know her better but feels guilty about what he did on the night Anna’s body was found. And though she wants to, Alex can't hide her true self from them. Not forever. Her desire for revenge is too strong.
But violence only breeds more violence, and Alex unwittingly sets off a series of events that will change her life and the lives of her friends forever.