Cheng Sai-gau transmigrates into the body of a detective in Shau Kei Wan, Hong Kong Island, where his sycophantic nature earns him contempt. Against the backdrop of police-gangster chaos in 1973, he activates an unlimited assassin system, discovering that with enough funding, he can have a continuous supply of assassins. Leveraging this advantage, he confronts challenges from various factions, solves funding problems, and gradually rises from a weak detective to one who controls the situation on Hong Kong Island.