Set in the 1820s during the early Risorgimento, when Italy was under Austrian control, it concerns the love affair of a young Roman princess and a revolutionary carbonaro.

The woman then reveals that she is in fact a man, Pietro Missirilli, a carbonaro and the nineteen-year-old son of a surgeon from Sant'Angelo in Vado.

Several times he plans to leave, but she persuades him to stay; she offers to marry him, but he refuses her in the interest of Italian liberation, and his nobility makes her love him more.

She succeeds in getting him to try to commute the sentence; besides her persuasion, he is also motivated by the thought that he is still young and may see a day when the execution will be a stain on his character.

When Missirilli and the other carbonari are transferred to a new prison, Vanina arranges to meet him in a chapel at midnight, where he will be chained and in sight of a jailer, but where their conversation will not be overheard.

He wishes to remain friends, advises Vanina to marry Savelli, and promises that the money she contributed to the cause will be repaid when Italy is free.

Vanina gives him the jewels she is wearing and files, so that he can use them to break his chains, but he asks her to forget him, for he is committed to dying for his country.

Roberto Rossellini (1906–1977) adapted this story to a film of the same title in 1961 starring Sandra Milo (Vanina) and Laurent Terzieff (Pietro).

In 1963, East German television broadcast a film based on the novel, starring Annekathrin Bürger in the title role, Peter Sturm as Asdrubale and Alfred Struwe as Savelli.