在某城市，Darker發放「死亡通知單」預告所有人，將在何時以何罪向何人執行死刑。即使收到通知單的人報案，得到警方的貼身保護，Darker照樣能突破重圍，手刃受刑人。

警方為此成立了專案小組，然而每次緝捕行動均失敗而回，只能眼睜睜地看著殺戮發生。專案小組成員羅飛，善於觀察和分析，每次都精準地分析出Darker的行動，但卻總是晚了一步。隨著案件陸續發生，羅飛發現，看似隨機的殺人事件，實際存在著千絲萬縷的關係，背後還隱藏著更大的陰謀，而Darker的真正身分亦漸漸浮現出來…

A killer called Darker has been leaving a death notification card after killing scumbags who evaded the law. Police reacted by forming a task force with the elite personnels from each field to capture the vigilante. But in reality, what each department did was dumping their best but most eccentric members to the task force.

There is the high IQ but low EQ criminalist Luo Fei, the ill-mannered profiler Mu Jian Yun, the inflexible captain Han Hao, the cowardly crime lab specialist Yin Jian, the gothic loving forensic pathologist Liang Yin, the hacker Zeng Ri Hua, and the volatile combat specialist Xiong Yuan. With each murder, the task force uncovers the crimes the victims had committed, at the same time, gets closer to finding the mysterious vigilante.

https://www.youtube.com/watch?v=f9dRdcI8Vmk