When the expert in Aztec hieroglyphs at the British Museum goes missing the police are called in. This is no ordinary case. The expert is the son of Lord Gilbert Soames, a governor of the museum who has specifically asked the investigators to help the police. Perhaps it is tied in with the recent consignment from the Pale City delivered to the museum, perhaps the young man has got himself in with the nefarious underbelly of London Society. The police grudgingly allow the investigators take the lead.