1941, Shanghai in early winter. Chen Wang is the most ordinary postman in the Jing'an Temple Post Office. He walks through the streets and alleys of the concession every day, delivering letters, money orders and packages. Until one rainy night, he delivered a letter without a sender and only saying "Detailed Information" to No. 76 Jisi Feier Road - the headquarters of the Wang Puppet Agent. Three days later, the recipient of the letter died suddenly, and No. 76 Began a secret investigation of all people who had come into contact with the letter. Only then did Chen Wang realize that he had unintentionally become a "dead mailbox" for an underground organization to transmit information. What he didn't know was that as early as three months ago, the Shanghai Military Station had put a question mark on his file. Now, two undercurrents are rushing towards the postman who just wants to survive.
