It is the story of an intelligent but confused young London bookbinder, Hyacinth Robinson, who becomes involved in radical politics and a terrorist assassination plot.

Amanda Pynsent, an impoverished seamstress, has adopted Hyacinth Robinson, the illegitimate son of her old friend Florentine Vivier, a French woman of less than sterling repute, and an English lord.

Florentine had stabbed her lover to death several years ago, and Pinnie (as Miss Pynsent is nicknamed) takes Hyacinth to see her as she lies dying at Millbank prison.

There Hyacinth meets the radiantly beautiful Princess Casamassima (Christina Light, from James' earlier novel, Roderick Hudson).

Just as in The Bostonians, which was published in the same year, the novel concerns a group with a specific purpose- in this case, anarchists- who aim to make use of a talented but naïve individual.

In the same way that The Bostonians revolves around various characters attempting to win the loyalty of Verena Tarrant, so too does The Princess Casamassima focus on Hyacinth Robinson, and his involvement in complex politics.

She appears alongside Paul Muniment in Anno Dracula 1895: Seven Days of Mayhem (2017), where she is a member of an anarchist council taken from G.K. Chesterton's The Man Who Was Thursday.