Spurius is a mercenary and assassin working in Rome in 44 BC. In early February he is hired by Mark Antony’s wife Fulvia to spy on Cicero and plan his assassination if necessary. Fulvia is tired of Cicero’s criticism of Mark Antony, and sees him as a hindrance to the political goals of her husband and herself.  Spurius begins to observe Cicero, and while doing so becomes swayed by the powerful arguments Cicero makes against the triumvirate. While spying, he is discovered by a female slave named Gualia, who threatens to expose him unless he helps her escape Rome. He agrees, telling her that he will do so once Cicero is dead. However, he begins to question his job and becomes caught between the ideas of the Optimates and the Populares. 

With the help of Gualia, Spurius masquerades as a slave in order to spy on a dinner party attended by many senators. After the party, Spurius inadvertently overhears Marcus Junius Brutus and Gaius Cassius Longinus talking about the plot to assassinate Julius Caesar. He decides not to inform Fulvia of this, fearing that Cicero, whom he has ironically come to respect, would be included as a conspirator and put to death. When she orders Spurius to assassinate Cicero the following day, he pretends to accept her order, but actually makes plans to escape with Gaulia that night. Before they are able to flee the city however, the pair are caught and imprisoned.

 Fulvia visits Spurius in prison, and he tells her of the plan to kill Caesar in an attempt to win her help. To his surprise, she already knows of the plot, and plans to use the chaos that will result to push her husband into a position of higher power. She leaves Spurius in prison, but he and Gaulia manage to escape captivity with the help of his criminal contacts. He sends an anonymous message to Mark Antony informing him of the plot, but Antony arrives too late to stop the assassination. Spurius and Gaulia take advantage of the confusion in the city to escape Rome and start a new life.