Twenty years ago, 4-year-old Ding Xiang witnessed her mother being brutally murdered, but the highly intelligent serial murderer escaped justice. This case became one of the top ten unsolved cases of the Public Security Bureau.
Twenty years later, Jingtian, a police officer who was obsessed with the case, slowly began to get closer to the truth by chance. At the same time, he also entered the mysterious world of Lilac, peeling off the cocoon and pulling out the silk. The love-hate entanglement of generations came to the surface with a murderer in a shocking mystery. However, Jingtian found that things were still not as simple as he thought...