1928. Manchuria. Itami, a young Japanese man, falls deeply in love with Cynthia, a beautiful Chinese girl. Their brief happiness ends when he is called home for his military service and they are forced to part. Returning sorrowfully from the train station where she has bid her lover farewell, Cynthia witnesses her brother's bloody murder at the hands of Japanese right-wing extremists.

Three years later, Shanghai has been unofficially occupied by Japan. The city is tense, rife with violence and barely contained anarchy. Cynthia - now known as Ding Hui - is working for Purple Butterfly, a resistance group planning to assassinate Yamamoto, head of the Japanese secret service. Itami is also in Shanghai, operating as a secret agent and reporting directly to Yamamoto. Arriving at Shanghai station to meet his fiancie, Szeto, a young Chinese man, is mistaken by the assembled resistance fighters for the assassin they have engaged to eliminate Yamamoto. Violence erupts and Szeto's fiancie is shot dead in the crossfire. Szeto escapes with the Purple Butterfly members, all of whom believe him to be the hired killer. Only Ding Hui realises the truth...

Thus three destinies are linked by chance, and three fates set in tragic motion.