In Philadelphia, USA, there is such a homicide investigation team, and the cases they are facing are not recent, but old cases from a few years ago or even more than ten years ago. Such a homicide is figuratively called the "Cold Case". Lilly Rush, as the only female agent in the Philadelphia Homicide Investigation Division, forms the absolute centerpiece of this TV series that focuses on investigating old cases. Her composure, alertness, and her slender pale face left an indelible impression on the audience. This CBS TV series began airing in 2003 and continues to be unique among the many crime-themed TV series with its unique charm to this day. Unlike CSI, where the crime investigation process is presented like a documentary, and is not supported by many of today's cutting-edge technology, there are almost no scenes similar to "CSI Season 8" and other series about using high-tech analysis of corpses to find clues, and her unique charm is that with Lilly's tenacity, she and her partners always do everything possible to find those who are still alive. Let those who live in the shadow of the past recall the tragedy that happened in the struggle of relief or pain, bring the audience to the different world decades ago, and let the real murderer be highlighted little by little in the different memories and confessions of the parties involved. And every time the truth is revealed, the audience will find an incredible ending, or tragic, or angry, or helpless. But no matter how unbelievable the crimes that took place back then, the passage of time will eventually soothe some of people's sadness. Cold Case is filled with a strong nostalgic color and a touch of sadness, or a kind of feminine warmth, which makes you gradually moved by each story, so as to leave some touches in your heart. The most touching part of the whole play is at the end, when the real murderer is brought to justice, Lilly can always see the dead people standing on the opposite street corner, smiling at her, as if they really thank her for making the unjust case clear. At that moment, no matter how hard the heart is, it will be deeply moved.