The Story of Zhang Hua

On a rainy night, Zhang Hua, unemployed for fourteen months, finds a rusty knife in the ruins of a demolition site. Two hours and forty minutes later, three people are dead, and he is arrested on the spot. The evidence is conclusive, and he confesses without hesitation. The case should have been closed quickly. But Detective Chen Ming discovers that the wounds on all three victims are nearly identical, the surveillance cameras repeatedly failed when the murders took place, and the knife can disrupt signals, correct the wielder’s swings, and even inject an unknown substance into the human body. This is no ordinary murder weapon. It is an experimental instrument that has been maintained for more than thirty years. As the “Blood Knife Case” from twenty-four years ago resurfaces, a codename hidden for years gradually comes to light: 706. But the real question isn’t what the knife made Zhang Hua do. It’s this: when someone can still stop, but doing evil has become “no longer difficult,” who is responsible?