Undeliverable

At the end of the Anti-Japanese War, a postman in Shanghai accidentally received an undeliverable letter and a money order. Around this letter, the Japanese and puppet military police, gang factions, military commanders, Chongqing, Yan'an, and the Americans started fighting. Why are you fighting over this letter, and to whom does this letter end up? The story has ups and downs, and the plot has twists and turns. Purpose: Struggle for victory in the Anti-Japanese War