In 1939, Shanghai intelligence agent Gu Yangshan (Han Dongjun)) kidnapped the blind cryptography expert and his Oxford alumnus Joseph Needham, forcing him to give up developing codes for the Japanese army.Ding Yi (Zhang Yishan), a supporting actor from Chaosheng Theater Company), who was originally hired by Joseph Needham to pretend to be himself, but he was inexplicably involved in this accident.

In order to undermine the research and development of the cryptographic system, Gu Yangshan had to continue to hire Ding Yi to pretend to be Joseph Needham and himself became his assistant.The two passed numerous tests and infiltrated the heavily guarded Japanese military facility.During the execution of their mission, the two were always on the verge of death.Not only must they destroy the development of the Japanese army's cryptographic system, but they must also beware of exposing the fact that Ding Yi is neither blind nor does he understand cryptography at all.