Mr. Li (Liu Hua), the boss of Chenggong Pharmaceutical, a century-old pharmaceutical factory, decided to sell real estate and land instead of selling drugs. He hired a Hong Kong executive, Ruan Dazhi (Lin Junxian), who was hired at a high price, to find a Japanese buyer, Mr. Miyashita. But Mr. Miyashita was only interested in the exclusive formula of Yulu San Shen tablets that can cure insomnia. Just when the negotiations between the two sides were deadlocked, the appearance of "mysterious man S" who claimed to have the secret formula made the negotiations even more confusing. Lin Yitai (Alec Su), the sales director of Chenggong Pharmaceutical Factory, is a severe insomniac. He works in a dreamlike state all day long, but he accidentally learns about the transaction between S and the Japanese buyer. After becoming a ghost hunter, Lin Yitai discovered that everyone, including his immediate superior Ruan Dazhi (played by Lin Junxian), the senior secretary An Qi'er (played by Chen Qiaoen) with whom he had an ambiguous relationship, and the charming assistant of the Japanese representative, Meichuan Mikiko (played by Hong Xiaoxi), had ulterior motives. Even his most trusted pharmaceutical factory employee Lao Song (played by You Liping) behaved strangely. Everyone was the best suspect! At this time, the inner ghost "Mysterious Man S" hiding in a corner knew everything about everyone's actions...