Libertus is passing the villa of his patron, Marcus Septimus Aurelius, when he sees an elaborate travelling carriage which has pulled up outside and is now blocking the road. Recognising that this may be an important visitor, Libertus approaches the carriage, intending to explain that Marcus is away, gone to Rome to visit his old friend Pertinax, who has recently been installed as Emperor. However, for his efforts, Libertus instead receives a torrent of abuse and the carriage-driver almost runs him down as he departs.

Libertus is badly shaken, but goes back to the villa the next day to find out why there was no gate-keeper in evidence to deal with the stranger. There he finds a gruesome discovery: the man is dead and hanging in his hut, and none of the other house-slaves are to be found. Worse things are to follow as news arrives from Rome which will turn the lives, not only of Libertus and his family, but the whole Empire upside down . . .