In S City, H Province, renowned entrepreneur Wang Hui is found dead in a luxury villa, setting off a thrilling mystery.
Zhang Hao appears to be the small-time owner of an adult novelty shop, but secretly he is a private detective. He unexpectedly receives a mysterious package containing a diary and a letter, drawing him into a dangerous game. Police captain Li Ming leads his team in carefully combing the crime scene, leaving no clue overlooked. He is resolute and courageous, with a strong sense of justice. Reporter Lin Yue relies on her keen news instincts to investigate far and wide, fearlessly digging for the truth.
As the investigation deepens, Zhang Hao discovers that the diary may be connected to Wang Hui's murder. But when a stranger breaks in, he finds himself in even greater danger. Meanwhile, Li Ming and Lin Yue work in their respective fields to uncover clues. They gradually discover a vast, mysterious organization lurking behind it all, one that seems to be plotting a terrifying conspiracy.
Working with private detective Lin Feng, Zhang Hao encounters obstacle after obstacle while searching for the "Shadow of the Dark Night." The mysterious organization keeps them under surveillance, their clues are destroyed, and men in black repeatedly try to kill them. Li Ming's investigation is obstructed at every turn, while key witnesses go missing or change their statements. Lin Yue also faces danger during her interviews. She receives anonymous threatening letters, but refuses to back down.
In the face of adversity, they keep searching. They find clues in a mysterious basement pointing to the "Land of Shadows," only to be attacked once again by the organization. In S City, where danger lurks everywhere, can they solve the mystery and stop the organization's conspiracy? Everything remains uncertain, and the path to breaking the case is shrouded in fog.
