Cast

In the late 1920s, Cai Zekang, from a prominent Ningde family, moved to Shanghai to study at Tongji University while secretly seeking Communist Party connections. After confirming his membership, he adopted the alias Cai Wei and was tasked with establishing a radio station in the Eyuwan Soviet area. There, he set up communications for the Red Fourth Front Army and trained new operators, using his mathematical skills to provide vital intelligence that supported the Red Army's efforts during a critical period.