Samonji, a reporter, receives a message on his answering machine from his friend Takada that says "stop it... zero plan! February." Learning that Takada is dead, Samonji begins an investigation. He and his younger sister Fumiko investigate major events happening in February but cannot find anything relevant. Meanwhile, Kanzaki, a doctor who works at a clinic on a remote island, is working on a plan to extort two billion yen.