Lustrum (US: Conspirata; 2009) is a historical novel by British author Robert Harris.

It is the sequel to Imperium and the middle volume of a trilogy about the life of Cicero (106–43 BC).

The book continues in the format of the first novel, with the story told in the first-person from the point of view of Cicero's secretary Tiro.

It follows on immediately from Imperium, starting with the beginning of Cicero's consulship and ending with his exile as a result of the enmity of Clodius.

This article about a historical novel of the 2000s set in ancient Rome is a stub.