Wishart's 1998 novel Sejanus is by far the best to date that I have read of his fictional works set in ancient Rome. From master to slave, the characters are drawn with Dickensian completeness. Each is memorable for personal traits and foibles; each is plausibly motivated and psychologically convincing. Even the women - in particular, the chief Vestal, Junia Torquata - are fully characterized and individuated.
In pursuing the clues left for him by Livia, Corvinus encounters a wealthy foreigner then resident in Rome, the Spaniard Sextus Marius, and his acquaintance with Sextus develops into a striking subplot. Sextus, it seems, fancies himself a Carthaginian, and holds the belief, maddening to a Roman, that the product of an incestuous union will produce an Uebermensch. Corvinus is instrumental in rescuing the girl, whom Wishart calls Marilla instead of Maria in order to avoid obvious associations, from her father's unwelcome and illicit embraces, which eventually led to his being convicted of incest and thrown to his death from the Tarpeian Rock in AD 33. His "Carthaginian" or north African belief seems analogous to the current superstition, said to be prevalent among South African natives, that having sex with a virgin will either cure or prevent AIDS.
The story is narrated in the first person by a Roman noble, Marcus Valerius Messala Corvinus, who, with his wife, Perilla, has returned to the capital from his voluntary exile in Athens to attend his father's funeral, and who is drawn into a leading role in a complex plot devised by the late Augustus Caesar's deceased wife, Livia.
The erstwhile power behind the throne, Livia had two objectives. The immediate one was to derail the plan of her son Tiberius to name as his successor the commander of the Praetorian Guard, Lucius Aelius Sejanus, who is his deputy in Rome. This is accomplished when Corvinus discovers and reveals to the emperor that his son Drusus died not from natural causes but from a slow poisoning, arranged by Sejanus, from a compound of antimony known as stibium, then used in cosmetics.
Livia's distant goal was to disgrace the Julians so thoroughly as to destroy any nostalgic public sentiment for their return to the imperial throne, and her means is Machiavellian: by ensuring the eventual accession of the youngest son of Germanicus (Tiberius's adopted son) and Agrippina, the thoroughly mad Gaius, better known as Caligula ("Little Army Boot"), who fancies himself a living god, for whom becoming emperor is merely a stepping stone.
The plot's intricacies are well constructed, and as they are unravelled the reader is presented with a panoply of graft, corruption, and greed at all levels of imperial administration.
Wishart's main sources are the historical Annals of Tacitus and the fictional I, Claudius of Robert Graves, the future emperor Claudius's secret memoirs. While his book can be read easily and understood fully by a novice to the sagas and mores of imperial Rome, a reader's appreciation of its characters and their historical roles will be greatly enhanced by first reading Graves' novel or viewing in its entirety the twelve-part BBC version of I, Claudius, recently reissued in both DVD and VHS formats, widely available for purchase, if not for rental, and well worth owning.