Classroom follows Ling a new substitute teacher, suspecting that some of her students in 4E engage in prostitution. Ling reports the problem only to be told by the Dean there was never a class 4E. In Travel, a group of friends go on vacation during which Bo gets killed in a road accident. After the funeral, Ka Ming reveals the secret of his relationship with Bo before going on a killing spree. Suspecting that her students Gi Gi, Co Co, and Fong engage in prostitution, Ling reports the problems with her class to the dean, only to be told that there has never been a Class 4E in the school... In Patrick Kong's Travel, a group of friends go on vacation in Mainland, during which Bo gets killed in a road accident. At Bo's funeral, her travel mates meet Bo's estranged lover Ka Ming , with whom Bo had a heated quarrel on the phone just prior to her tragic death. At the hot-pot dinner after the funeral, a pale-faced Ka Ming reveals to the survivors the secret of his relationship with Bo before going on a killing spree...