The Princess Casamassima.

A superior set of Henry James' ninth novel, often considered a companion piece to The Bostonians (1886) and a seemingly unusual work in the author's canon, both for its tackling of a relatively violent theme & plot-line and for its use of a recurring character, Christina Light, the mademoiselle fatale of Roderick Hudson (1875), who was married off by her mother at the end of that novel to the Italian Prince Casamassima.

The chief protagonist is London bookbinder, Hyacinth Robinson, a young and slightly naive man who becomes involved in radical socialist politics and a terrorist assassination plot, set against a backdrop of London, France and Italy.