Who owns the Eustace Diamonds? Lizzie Eustace claims that Sir Florian Eustace, her late husband, gave them to her. But Mr Camperdown, the family solicitor, insists that they are an heirloom, to be passed down from generation to generation. Lizzie is both beautiful and clever, yet Mr Camperdown believes her to be a scheming liar. And Mr Camperdown is right! The battle for the diamonds rages until a robbery intervenes and they disappear. Or do they...?