The narrative follows solicitor Peter Daventry when an American collector's passion for royal relics entangles him in a pair of murders, one at an art gallery and another at a country estate. Daventry and the eccentric Mr Bathurst probe books, screened portraits, a mysterious catalogue number, and memoir fragments while Inspector Goodall pursues formal inquiries. The investigation unravels through careful examination of provenance, hidden panels, and subtle social clues, presenting a methodical puzzle of detection that interweaves antiquarian obsession, manners, and deductive reasoning.