The murdered body of a visiting ambassador from Rome is discovered in the temple of the Imperial cult and once again freedman and pavement-maker Libertus is called upon to investigate. Events take a bizarre and chilling turn when the body disappears, and then unearthly wails are heard coming from the temple and mysterious bloodstains start to appear from nowhere. But Libertus is sure there is a more human explanation for the murder and he is to uncover still more unsettling events before the truth is finally revealed...