In the early years of the Republic of China, there were turbulent times and undercurrents. The bustling Shanghai Beach is not only a paradise for adventurers, but also a breeding ground for crime. The young Gu Yuan, relying on his extraordinary powers of observation and meticulous logical reasoning, became a famous private detective in Shanghai. Not only does he have to face an endless stream of strange cases, he also has to deal with intricate social relationships and battle wits with cunning gangsters, insidious warlords and all kinds of characters. Behind every case, there are unknown secrets and conspiracies. How will he use wisdom and courage to clear away the layers of fog and reveal the truth? Will you stick to the justice in your heart in troubled times? Let's see how Gu Yuan gradually became the veritable "No. 1 Detective of the Republic of China" in the foggy Shanghai!
