"The Longest Day in Chang'an" is a Chinese historical drama set in the Tang Dynasty. The story follows a former detective and a mysterious woman as they work together to prevent a terrorist attack in the city of Chang'an. As they race against time to uncover the plot, they must navigate through political intrigue, betrayal, and danger. The drama is filled with suspense, action, and unexpected twists that keep viewers on the edge of their seats. Will they be able to stop the attack and save the city before it's too late?