On lonely urban nights, radio DJ Simon (Lei Yuyang) often receives calls from his listener Cat (Yen Zidan) to express his feelings. Cat hangs up, picks up a gun and becomes a cold-blooded killer. He rushes into a building and kills all the targets and bodyguards. The team of policewoman Carrie (Wu Chenjun) took over the case. Carrie, who listens to the same program every day and is quite familiar with Cat's voice, doesn't know that Cat's image has already appeared in her mind... Cat runs into his old friend Wesley (Huang Jianuo) while performing a new mission. It turns out that the two were both American police officers...