Hong Kong 1938
During the Second Sino-Japanese War, a shy, inexperienced university student, Wong Chia Chi, travels from Shanghai to Hong Kong and attends her first year at Lingnan University. A male student, Kuang Yu Min, invites her to join his patriotic drama club, and soon she becomes a lead actress, inspiring both her audience and her colleagues. Inspired by the troupe’s patriotic plays, Kuang persuades the group to make a more concrete contribution to the war against Japan. He devises a plan to assassinate Mr. Yee, a special agent and recruiter of the puppet government of Wang Jingwei set up by the Japanese occupation in China. The beautiful Chia Chi is chosen to take on the undercover role of “Mrs. Mai”, the elegant wife of a trading company owner. She manages to insert herself into the social circle of Mrs. Yee.
Chia Chi catches the eye of Mr. Yee and tries to lure him to a location where he can be assassinated. Chia Chi is still a virgin, and she reluctantly consents to having sex with another student involved in the plot, in order to practice her role as a married woman if she were to sleep with Yee. Kuang, who has feelings for Chia Chi, is upset by this, but agrees to the arrangement. Attracted to Chia Chi, Yee nearly falls for the trap but withdraws at the last minute. Soon after, Mr. and Mrs. Yee suddenly move back to Shanghai, leaving the students with no further chance to complete their assassination plan. While they are preparing to disband, an armed subordinate of Yee turns up unannounced and tells them that he is aware of their plans. After a violent struggle, the university students kill the subordinate and then go into hiding.
Three years later in Japanese-occupied Shanghai, Chia Chi again encounters Kuang, who is now an undercover agent of the Kuomintang (KMT) secret service the Juntong, which is seeking to overthrow the Japanese occupation forces and their puppet government. He enlists her into a renewed assassination plan to kill Yee. By this time, Yee has become the head of the secret police department under the puppet government and is responsible for capturing and executing Chinese resistance agents who are working for the KMT. Chia Chi is trained to use weapons and other spy tools. She eventually becomes Yee’s mistress, and during their first encounter, Yee has coercive sex with her. Over the next few weeks, however, their sexual relationship becomes more intimate, which causes conflicting feelings in Chia Chi, who is still involved in the assassination plot.
When Chia Chi reports to her KMT superior officer, she exhorts him to carry out the assassination soon so that she will not have to continue her sexual liaisons with Yee, but she is told that the assassination needs to be delayed for strategic reasons. Chia Chi describes the inhuman emotional conflict she is in, sexually and emotionally bound to a man whom she is plotting to assassinate. When Yee sends Chia Chi to a jewelry store with a sealed envelope, she discovers that he has arranged for a large and extremely rare six-carat pink diamond for her, to be mounted in a ring. This provides the Chinese resistance with a chance to get at Yee when he is not accompanied by his bodyguards.
Soon after, Chia Chi invites Yee to accompany her to collect the diamond ring. While entering the jewelry shop, she notices that all her friends involved in the assassination plot are stationing undercover outside. When she puts on the ring and sees Yee’s obvious love for her, she is overcome by emotion and quietly urges him to leave. Understanding her meaning, Yee immediately flees the shop and escapes the assassination attempt. By the end of the day, most of the resistance group are captured. Yee’s deputy was aware of the resistance cell, but did not inform Yee because he hoped to use the opportunity to catch their leader. Emotionally in turmoil, Yee signs their death warrants and the resistance group members, including Chia Chi, are led out to a quarry and executed. As all the members of the resistance group are forced to their knees while the executioners take out their pistols, a sad Kuang, who always loved Chia Chi, gazes at her. Meanwhile, Yee sits on Chia Chi’s empty bed in the family guest room while his wife asks him what is going on, since his secretary and two men had taken Chia Chi’s belongings and some papers from his office. Yee tells her to keep quiet and to continue playing downstairs, to avoid letting anyone know that something is amiss. If anyone asks, he says, Chia Chi has returned to Hong Kong.