The Lady Lizzie Eustace, a beautiful young widow, claims that her husband gave her the extremely valuable diamond necklace to be her very own. However, Mr. Camperdown, lawyer for the estate, says that it is a family heirloom and must be given up. Lizzie, for whom lying is always more natural than telling the truth, stubbornly clings to the diamonds, taking them with her everywhere, rather than entrusting them to some safe depository.
But then there is a skillfully performed burglary, and the jewels are stolen from her hotel room in Carlisle. Or are they? Did Lizzie just use this scheme to make the diamonds disappear? Why is there a second burglary at her London apartment? The novel becomes a fascinating detective story.
Lizzie longs for a husband to share her problems. But which man is it to be? There is Lord Fawn, to whom she is engaged, but who breaks with her because of the diamonds. Lord George, a rather shady character, intrigues her with his swashbuckling mann! ! er. Then there is her ever loyal cousin, Frank Greystock, but he is supposedly engaged to a penniless nonentity, Lucy Morris.
Lizzie Eustace is one of Trollope's most interesting characters--beautiful, strong willed, intelligent in her way, but utterly untrustworthy, constantly scheming to get what she wants and always able to justify her actions to herself. It is no wonder that even the similarly mendacious Lord George is afraid of her. Lizzie alone makes this third novel of the Palliser series well worth reading.