In the autumn of 2002, Chen Xi, a female college student in Linjiang, died in a rented house. The scene was spotless, with only a tiny puncture needle embedded in her chest - no fingerprints, no footprints, and no traces of any biology. In the past six years, a series of murders occurred one after another, and the scenes were exactly the same. The only thing left was the medical needle that had been discontinued long ago.
Detective Lu Chen has been chasing the murderer for six years, from being full of passion to being suspended for self-reflection, from mistakenly arresting innocent people to recovering evidence. The murderer always hides in the dark, uses public phones to provoke, and uses anonymous black cards to declare war. Every time he commits a crime, his techniques are polished to perfection. When the three physical evidence locks were closed, the murderer stood in the interrogation room and silenced all accusations with zero confession.
Six needles, six lives, a truth that has been sealed in dust for thirteen years. When the last stitch fell, Lu Chen discovered: the cleanest crime scene hides the uncleanest past; and the real flaw is never in the evidence, but in the most paranoid corner of the human heart.
