Eternal Wave 密战 is a Chinese film set during the anti-Japanese occupation era starring Aaron Kwok, Zhao Li Ying and Zhang Han. It follows the main protagonist Lin Xiang who is a spy working underground to reestablish what was destroyed ruing the Battle of Shanghai. He meets a simple yet patriotic young lady who becomes his partner as they infiltrate the enemy as a couple. Apart from that, they cross paths with Liang Dong, a man whose motives are unclear.
After the death of her policeman father, Xiaomai begins to look over his old journals filled with notes about the cases he investigated over the years. The mention of a purple scarf in the notes particularly catches her attention, prompting her to purchase a similar scarf from a mysterious website that claims to sell everything, as long as one can pay the price. Soon after, Xiaomai's close friend is found dead, strangled by a purple scarf. All of this awakens Xiaomai's memories of her childhood sweetheart Qiushou, whose mother was also strangled to death with a purple scarf by an unknown killer. Xiaomai and Qiushou grew up together and fell in love, but he suddenly disappeared from her life 15 years ago without a word. She begins to believe that Qiushou has returned and may be seeking revenge.
A sister and brother, the last heirs of a family of acrobats, are called upon by a Buddhist monk sect to retrieve an artifact that their ancestors have protected throughout the ages.