Kang Ho, a passionate firefighter, dedicated everything to his mission of rescuing many people out of a sense of duty. However, what he get back was a burned and brutally murdered wife, and the betrayal from the world. Determined to seek revenge in his own way, even though he saved them, he decides to reclaim the lives of those he deems unworthy of living a new life. He then raises his daughter, Mina, to become a ruthless killer in order to carry out his vengence. As time passes, 10 years later, Kang Ho believes that his daughter has become a complete killer as a high school student. He assigns her the first mission to retrieve the life of a designated target…