This is a short, fierce book about a plot to overthrow Rome from the inside. The writer is Sallust, a politician who left public life and turned to history. The year is 63 BC. A bankrupt nobleman named Catiline gathers debtors, old soldiers, and desperate men, and plans fire and murder while Cicero — one of the two consuls, the officials elected to run Rome for a year — tries to stop him in the Senate.

Sallust is not writing a detective story so much as a warning. He thinks luxury and greed have worn down the old Roman character, and Catiline is what that looks like when it picks up a sword. The plot is caught. Rome survives. The men who die in the last fight are Romans, killing Romans.