Unlike CSI, which presents the process of criminal investigation like a documentary and without the support of many of today's cutting-edge technology, there are few scenes similar to CSI about using high-tech analysis of corpses to find clues. Lilly Rush, as the only female agent in the Philadelphia homicide department, forms the absolute core of this TV series with the theme of investigating old cases. Her calm, alert and sharp face, as well as her slender and pale face, left an indelible impression on the audience. the unique charm of this play is that with Lilly's tenacious character, she and her partners always do everything possible to find those parties who are still alive, so that those who live in the shadow of the past can recall the tragedies that happened in a gratifying or painful struggle. Bring the audience to the different world of a few decades ago, so that the real killer stands out in the different memories and confessions of the parties concerned. And every time the truth is revealed, the audience will find an incredible ending, or tragic, or angry, or helpless. But no matter how incredible the crimes that occurred that year, the passage of time.