In 2756 AC (2003 AD in Christian terms), magnetic railways span Roman territory from Persia to Terranova, and mechanised crucifixes are ranked along the banks of the Thames. As volume one of ROMANITAS opens, Marcus Novius Faustus Leo, heir apparent to the Imperial throne, is mourning the death of his parents following a tragic accident. However, as information about the last days of his father's life becomes known to him, Marcus realises that his father's death was no accident and that his own life is in danger. Meanwhile, an escaped slave girl called Una, who possesses the power to look inside others' minds, struggles to save her brother, Sulien, from a London prison ship. In a fortune teller's stall in a Gallic flea-market, Marcus, Una and Sulien's paths cross, and the fate of the Empire rests on their shoulders...