The Detective Boys receive a letter by airmail at the Moore Detective Agency. Originating from Egypt and signed by a sender who calls herself Cleopatra, the letter warns that a 4500‑year‑old pharaoh’s curse may be reawakened. To prevent this, seven riddles, each linked to pyramids, must be solved within a short time. Though Moore is in a drunken stupor and offers little assistance, Ran agrees to help the children. The Detective Boys then set out to answer the seven questions posed in the letter.