Following a murder at a party, detective Jimmy (Shinichi) Kudo is called upon to solve the case. He reveals that the host is the murderer and the case is closed. Jimmy and his friend, Rachel Moore (Ran Mouri), then take a trip to an amusement park where they find that a man has been decapitated during a roller coaster ride. The two men then attack Jimmy from behind and force him to take a newly developed poison.