Mia Isn't a baby girl

She is a deranged gangster looking for her revenge. She kills first and questions later. She waited for too long to take her revenge, and when she finally got the chance to... He stopped her. Things fell apart. Nothing worked for her. She lost everything, even her only friend. She lost all hope. She is a gangster, he is an ordinary boy. Would she be able to get her revenge or will he stop her?