The heiress of the family that owns a well-known corporation arrived at the event celebrating the sixtieth birthday of the magnate Goro. Reiko made a sensation with her beauty. However, she made a blunder as she stumbled and fell, but the beauty managed to handle the embarrassment as if someone had given her a hint. And she is not just an ordinary girl, and certainly not a dummy. The heroine receives a call from her friend, who informs her that an incident has occurred at the hotel and she needs to go there. She hides her identity from her colleagues, but luckily someone brings her work clothes. She doesn't want other police detectives to perceive her differently.
It becomes known that one of her acquaintances, Mizuho Tesirogi, is injured. Before her death, she manages to describe the distinctive characteristics of the person who hit her on the head. Inspector Kadzamatsuri believes that statements should be taken from all the ladies dressed in red dresses. However, the suspicious girl also had a pendant with an emerald. The guy throws loud suspicions, but the cousin of the victim interrupts the conversation with the girls. The most unimaginable secrets start to unravel. The heroine and the expressive detective intend to bring the investigation to a conclusion.