For her mission, Mia flew from Chicago to California. Because Mia is a bright girl who never fails to complete a task, her boss always knows to rely on her. Since she was fifteen years old, she has worked for Underworld. Mia is friendless and devoid of maternal affection. The goal is to assassinate or eliminate Ryan, a young billionaire who took over his father's business following his murder. Ryan's father was slain one day before his birthday, leaving him with terrible memories. Seeing his father lying there in a pool of blood, Ryan vowed to kill whoever did it. Since then, the only thing that could be done was exact revenge. But what will happen when he falls in love with the person who murdered his father??