The protagonist Chen Mo was originally an ordinary funeral shop owner, but he received a mysterious black package on his birthday and has since become the "Yin Division Courier" connecting the two worlds of Yin and Yang. He needs to deliver the items from the underworld to the designated person in the upper world, or send the items from the upper world to the underworld. Behind every express delivery, there is an unresolved grudge, a dusty unsolved case, or a secret of yin and yang that subverts cognition.
