Takahashi Erika got married a year ago and has been leading a happy life with her husband, Takahashi Ryosuke, a company employee, and Kotaro, his young son from an earlier marriage. One day, a man shows up in front of her. He is Tozuka Soichi, her former boss from the Cabinet Information Research Office's Special Division. Erika had been a secret agent under Tozuka until a year ago. Tozuka has left the Cabinet Information Research Office and is now the head of a company that carries out background checks and investigations into infidelity by making use of his experience from his spy days. He thinks highly of Erika's skills and would like her to help him in his work. Faced with the threat of having her secret past revealed to her husband, Erika is half compelled to assist Tozuka. The first client is a young lady called Takeuchi Hitomi. Hitomi had signed up with a matchmaking agency and met a doctor by the name of Hayami at one of its parties. The doctor had taken a drunk Hitomi to a private room where he made her drink alcohol laced with sleeping pills and got violent with her. Erika transforms from a good wife and kind mother into a callous spy in order to expose the wrongdoings of Hayami and retaliate against him...