Cold Case is different from CSI in that it presents the criminal investigation process to the audience like a documentary, and it is not supported by many cutting-edge technologies today. In this drama, there is almost no scene similar to CSI about using high-tech to analyze corpses to find clues. Lilly Rush, as the only female detective in the Philadelphia Homicide Investigation Department, is the absolute core character of this TV series with the theme of investigating old cases. Her calmness, alertness, and her slender and pale face have left an indelible impression on the audience. The unique charm of this drama lies in that, with Lilly's tenacious character, she and her partners always try their best to find those parties who are still alive, so that those who live in the shadow of the past can recall the tragedy that happened in the past in either relief or painful struggle, bringing the audience to the different world decades ago, and allowing the real murderer to emerge little by little in the different memories and confessions of the parties. And every time the truth is revealed, the audience will find an incredible ending, which may be tragic, angry, or helpless. But no matter how incredible the crime that happened that year was, the passage of time will eventually soothe some of people's sorrow. The whole series of Cold Case is filled with a strong nostalgic color and a touch of sadness, or a kind of female warmth, which makes you gradually moved by each story, leaving some touches in your heart. The most touching part of the whole series is at the end. When the real murderer was brought to justice, Lilly always saw the people who died that year standing on the opposite street corner, smiling at her, as if they really thanked her for redressing the injustice. At that moment, even the hardest heart will be deeply moved. The seventh season will open with a missing girl on a ship more than 40 years ago, which was identified as suicide.