A plot summary, from the author:
It is the Season of Misrule in Rome, sheer misery for Falco. Uppity slaves give orders to their cringing masters, masters try to hide in their studies, women are goosed, statues wobble, a prince has a broken heart, Helena’s brother will not decide if his heart is broken or not, children are sick and even the dog can’t stand it any more. As the festival meant for healing grudges riotously proceeds, a young man who has everything to live for dies a horrific death while the security of the Empire is compromised by the usual mixture of top brass incompetence, bureaucratic in-fighting and popular indifference. The barbarians are not just at the gates, they are right inside - and that’s just the bombasts in the Praetorian Guard, encouraged by the pernicious Chief Spy.
Doctors are making a killing. Alternative therapists are ecstatic. Members of the Didius family are about to receive some extremely unusual seasonal gifts. But for the non-persons on the fringes of society life is not so jolly, and dark spirits walk abroad (available for hire through the usual agents). Falco has a race against time to find a dangerous missing person, aided and hindered by faces from the past, while running the gauntlet of the best and worst Roman society can offer as Saturnalia entertainment. Unfortunately for him.