In the chaos of the Nanjing air defense drill in 1937, Zhou Mo, an underground party member named "Watchmaker", witnessed the assassination of a liaison officer.
>Before he died, the liaison officer gave him half a piece of jade: "Find the 'butterfly'... Stop the 'Sakura Festival'..."
>Almost at the same time, Anna, a Jewish cryptography expert, fled to Nanjing. The codebook entrusted to her father before his death was coveted by the Japanese Super High School;
>Qing Gang gangster Jin Xiaodao was accidentally involved in the conspiracy of the Japanese army's secret biochemical warehouse because his master was kidnapped.
>Three people who don't know each other, each performing seemingly unrelated tasks:
>Zhou Mo traced the clues about Yuhuang and discovered that the "butterfly" was actually related to the secrets of the Japanese royal family;
>The coded message decoded by Anna points to the same warehouse, but it leads to a mad pursuit by the Super High Class;
>In order to save the master, Jin Xiaodao accidentally ignited the fuse in the warehouse.
>When the explosion illuminated the Yangtze River, the three looked at each other in shock - their operation code name was "Butterfly".
