For three years, a serial killer has walked among the citizens of Hangzhou, China. With each new body come the same clues: a jump rope, a cigarette, and a slip of paper that says, Come and get me.

In the same city, Luo Wen wanders into a park just as a young woman stabs a local thug to death in a desperate act of self-defense. A former criminal investigator who lost his own family in an unsolved case, Luo Wen is familiar with the slippery nature of justice. So he makes the split-second decision to help the terrified woman cover up her crime, leaving behind no trace of...