"This is your last chance!! Reiko, please..." Reiko, who had retired from undercover investigation after getting married, is asked by her husband to go back as an investigator and infiltrate a casino where an organization is hiding out. Reiko poses as a customer and tries to make contact with Sagawa, a senior member of the organization, but she does not reveal her true identity. Reiko gets a male accomplice to arrange an opportunity for her to make contact with Sagawa, but her actions are known to Sagawa. Then, alone with Sagawa in a hotel room, Reiko learns his true identity...