Sook-hee is a trained assassin who was Honed from childhood into a merciless killing machine by a criminal organization in China. After the death of her mentor, when the chance of starting a new life is given to her, she comes to South Korea as a government sleeper agent. They promise her, that she would be free after ten years of service. So after 10 years, she begins her new life - and she hopes for the chance for a normal life.

But soon enough, secrets from her past destroy everything she’s worked for, and now nobody will stand in her way as she embarks on a roaring rampage of revenge - leaving a trail of bodies behind her.