Anno Mortis gleefully features a cast of gladiators, lions, jackal-headed monsters, Roman emperors, black magicians, Norse gods and zombies. The latter, of course, being the key addition to this otherwise historical (cough) narrative. Levene clearly has done her research, and has populated this this necromantic alternate history with enough classical trivia to keep even the most educated reader on their toes. Kind of like Rome, except with more zombie tigers.
Anno Mortis tells a (slightly) fictionalized version of the last days of Caligula's reign. The mad emperor, distraught and distracted over the death of his sister/lover, Drusilla, presides over an empire that is crumbling into decadence and ruin. Behind his back, the sinister Cult of Isis gathers power, influence and the occasional human sacrifice.
Into this mess plunge Boda, a gladiator, Vali, a bard from the barbarian north, Petronius, a spoiled ppatrician teen, and Narcissus, the favored slave of the Emperor's stuttering uncle Claudius. As each follows their separate trails, these four unlikely heroes uncover the nasty secret of the Cult (Hint: Zombies), and set off a chain of wild events (Hint: More zombies) ending in an epic showdown on the streets of Rome (Hint: Great whacking stacks of zombies).
Although the author does wink a bit towards more established histories of the Roman empire (virtually all the characters in the book are historically significant), classical knowledge isn't a must. Nor, although Levene gleefully demonstrates a Gaiman-like knowledge of mythological themes, is any prior knowledge of Roman, Egyptian or 'barbarian' (Norse...) folklore. These added layers do, however, demonstrate that Anno Mortis is more than would initially meet the eye (given the cover's zombies and chainmail bikini).
All said and done, Anno Mortis is a massively entertaining - and oddly educational - romp. From sieges to orgies; tigers to chariot races; it pulls out all the stops in providing unceasing fun.