Allan Massie's novels about the Roman empire - Augustus, Tiberius, Caesar, Antony and Nero's Heirs - put human faces to some of history's most notorious characters. In this account of Caligula, he examines whether the emperor was a murdering lunatic - or 'sane, horribly sane; that he had seen the void and accepted it, knew human life for what it is, or may be: a vast emptiness'. The story is narrated by Caligula's adviser Lucius. When Caligula first comes to power, he causes a scandal by sleeping with his sister, Drusilla, and the actor Mnester. After Drusilla dies, he decides he needs a wife and tells Lucius: 'I think I'll take yours.' Massie's evocation of the period is impressive, but it can be tedious, especially in the early chapters where he painstakingly lays out the genealogical background of the imperial family.