Five Chinese young people go for an outing, encountering a little girl blocking the road for help. To save the girl, they got into a chemical factory and got involved in a catastrophe of mutant rats attacking human beings.

While investigating a murder in the old city, Public Security investigator Song Xingye uncovers a hidden conspiracy. Teaming up with his tech-savvy assistant Zhen Na, tough police officer Shang Wei, and the mysterious heiress Zhao Qingyun, he races against time to expose the truth and stop a looming coup.