陈杰（麦浚龙饰）以卖包为业，偶然之间结识了有些弱智的女学生张颖（苍井空饰），在不断的交往中，二人之间互生情愫。一天，警察队长杜哥（刘永饰）在醉酒后遇到了张颖，他误以为张颖是街头的站街女，于是上前拉扯并要跟她发生关系，陈杰看到后上前阻止并将杜哥打伤，随后他把张颖带走。二人决定去警局报案，结果正好去了杜哥所在的警局，结果可想而知，张颖被杜哥为首的一群黑警轮奸，陈杰在被毒打后扣上罪名扔进了监狱

几年后，陈杰刑满被释放，他早就酝酿着复仇计划，随着连续两起凶案发生，有两个孕妇被强行剖腹取子，而这两名孕妇的丈夫一死一失踪，巧合的是，两名男死者均是同一便衣团队。与死者同一团队的队员谢夫（钱小豪饰）和国华（何华超饰）觉得事情不妙，他们立刻联系了已经退休的队长杜哥，把事情告之后劝其小心行事，谢夫有一个不祥的预感，他认为这个冷血杀手的目标就是他们的便衣团队。

Chen Jie (Mai Junlong) sells bags for a living, and accidentally meets a mentally handicapped female student Zhang Ying (Aoi Sola), In the constant communication, there is mutual affection between the two. One day, police captain Du Ge (played by Liu Yong) met Zhang Ying after he was drunk. He mistook Zhang Ying for a street girl on the street, so he pulled her up and wanted to have sex with her. Chen Jie stepped forward to stop her when he saw it. And wounded Du Ge, and then he took Zhang Ying away. The two decided to go to the police station to report the case, and they happened to go to the police station where Du Ge was. As you can imagine, Zhang Ying was gang-raped by a group of black policemen headed by Du Ge. After being beaten, Chen Jie was charged and thrown into prison.

A few years later, Chen Jie was released after serving his sentence. Two pregnant women were forcibly taken by caesarean section, and the husbands of the two pregnant women died and the other disappeared. Coincidentally, the two dead men were from the same plainclothes team. Xie Fu (played by Qian Xiaohao) and Guohua (played by He Huachao), members of the same team as the deceased, felt that something was wrong, so they immediately contacted the retired captain Du Ge, and advised him to be careful after telling the matter. With a hunch, he thought that the target of this cold-blooded killer was their plainclothes team.