On an ominous night of a violent storm, Xin Helen (Anita Yuen), a single mother who is a yoga instructor, was driving home with her daughter Sisi (Zhang Zimu) when they were suddenly stopped by a black car. When the mother and daughter regained consciousness, they found that someone had changed them into red clothes and they were in a cold cave. After that, Helen met seven other men and women who had never met before. These people had different professions and did not seem to know each other. Then a mysterious voice came, announcing that they would have a death party next. There was a killer among the nine people, and the killer would kill these people every time the hypnotic gas attacked. They must find ways to find the real murderer and walk out of the death cave alive. After a series of suspicions and accusations, they killed each other and blood splattered. And Xin Helen, who had experienced all this, seemed to have to face the most secret side of her heart in front of the cold female detective Jenny (Xiong Naijin)...