The third novel in the Palliser series, The Eustace Diamonds is a satirical study of the influence of money and greed on human relationships in Victorian society.

The story follows two contrasting women and their courtships. Lizzie Greystock and Lucy Morris are both hampered in their love affairs by their lack of money. Lizzie’s trickery and deceit, however, contrast with Lucy’s constancy.

Lizzie Greystock, determined to marry into wealth, snares the ailing Sir Florian Eustace and quickly becomes a widow. Despite the brevity of their marriage, Lizzie inherits according to the generous terms of Sir Florian’s will, which include the Eustace diamonds. When the Eustace family solicitor, Mr. Camperdown, begins to question her legal claim to the family heirloom, Lizzie weaves a tangled web of deception and crime to gain possession of the diamonds. Enlisting the aid of her cousin, Frank, much to the dismay of Frank’s fiancée, Lizzie seeks to avoid legal prosecution while pursuing one love affair after another.

In this third novel of the Palliser series and the one least focused on the politics of the time, Trollope was understood to be commenting on the malaise in Victorian England that allowed a character like Lizzie, who marries for money, steals the family diamonds, and behaves despicably throughout, to rise unscathed in society.

Trollope's The Eustace Diamonds blends elements of mystery, politics, and romance in a memorable work.