Bai wakes up in a back room, losing all her memory. She meets Inspector Fong who is looking for his wife. With the help of Fong, Bai gradually recalls everything. The death of Bai's fiancé (the hostage) was indirectly caused by Fong's shootings. Bai also hurt her head and lost her memory...白小姐在密室甦醒，遇見警員方正良尋找失蹤的妻子，自己竟沒法回想前事，二人於是合力尋找真相。在正良幫助下，她終於發現了實情。原來正良在鬧市裡槍殺劫匪時，人質（白小姐的未婚夫）受驚過度而精神出現問題，最終跳樓而亡，她則腦部受創而失憶......
