Sook-Hee is a trained assassin who was born to kill. She was just a little girl when the training started in China. And after the death of her mentor, when the chance of starting a new life was given to her, she came to South Korea as a government agent. The National Intelligence Service promised her freedom after ten years of active assignments. So begins her new double life as a theatre actress-cum-hit-woman until the dark secrets from her past start to reappear. Then she gets a new mission and it changes everything.