At two o'clock in the morning, unemployed young man Lu Chen found a package under the door of the self-service library. The recipient's name was his, and he never told anyone he would be there.
The package contained a non-existent stamp, a bottle of luminous liquid, and a letter of acceptance - he was selected as the No. 37 Messenger in G City, responsible for delivering those letters that "no one can deliver".
The recipient has expired and the address has been abandoned. Instructions for newbies read: Do not enter the delivery point after midnight, do not open letters, and do not ask for the recipient's information. Those who violate the rules will be "logged off".
Lu Chen thought it was just a strange job until he discovered that the recipient of the first letter had died three years ago. The sender of that letter is something called "Rules".
As strange letters were delivered one after another, Lu Chen gradually came into contact with the huge and ancient system on the dark side of the city. Some call them postmen, others call them messengers. And they themselves know that the destination of every letter is a road of no return.
