Fleeing from Shenzhen police on a motorcycle, Li Shan-shan (Choi) loses control of the bike and goes off an embankment into the ocean. She washes ashore some time later with amnesia, is taken to prison, and sentenced to hang. Flashbacks show how Shan-shan's boyfriend, Liang Chun-hwa (Michael Tse Tin-wah), convinces her to participate in a scheme with Ted Hwang (Anthony Wong Chau-sang). The latter's father has recently died and left him with a large sum of money but Ted can only collect it if he is married. Teetering on the edge of bankruptcy, Ted offers Shan-shan $600,000 if she will agree to be his wife, a plan that Chun-hwa heartily endorses, as he wants the money to open a restaurant. While taking a physical in preparation for the wedding, Ted and Shan-shan learn that they share the same rare "HR" blood type. They sign the necessary forms but Chun-hwa clearly has trouble dealing with the situation. Ted and Shan-shan then meet with solicitor Chen Chi-pang (Chan Kin-pang), who gives Ted the document he must endorse to get his father's estate.
Not surprisingly, Ted has other plans for this business deal, slipping a drug into Shan-shan's drink and then raping her. He also takes compromising pictures of the woman and threatens to show them to Chun-hwa unless she continues to be his sexual plaything. When Shan-shan and Chun-hwa confront Ted, a scuffle ensues and the blackmailer is stabbed. Thinking that they have killed him, the couple flee the scene but Chun-hwa sees a way out: if Shan-shan consents to a blood transfusion for Ted, it will save his life. He is the only hope they have to prove their blackmail story and, even if he does pull through, there is no guarantee that Ted will tell the authorities the truth. Meanwhile, Chen has taken an interest in the case and, with the aid of his foster father (Eddy Ko Hung), does what he can to help Shan-shan out of this mess.