Late Spring, 455 AD. After a brutal winter struggle against the High King Vortigern, outcast imperial officer Ambrosius Aurelianus has led his weary followers to south-west Britannia in search of his mother's kinfolk. But Vortigern, thirsting for revenge is already forging a dangerous alliance against him. Taking refuge in a ruined Roman fort near the decaying town of Vindocladia, Ambrosius finds an ally in Lurotriga, the widowed queen of the Durotriges. Though still sworn to his Saxon lady Inga, he is soon beguiled by the British noblewoman. Between Inga and her new rival there can be no compromise and their enmity threatens to cause a rift between the Britons and Saxons of Ambrosius’ company. If Vortigern attacks before the fort is repaired Ambrosius fears the outcome. He must find allies fast but, in a land of squabbling rival tribes the Roman encounters more enemies than friends. A treaty with neighbouring Dumnonia offers Ambrosius some hope, but commits him to defend the south coast against Scotti raiders. Ambrosius’ forces are stretched perilously thin putting the lives of Lurotriga and others at risk. As Ambrosius prepares to pursue Vortigern for a final reckoning, his quest to discover his mother's kin suddenly delivers a startling revelation, but will it help him to defeat the High King? Heavily outnumbered in the thick forests and steep valleys of Vortigern's homeland, Ambrosius must rely upon the fighting spirit of his small force of bucellarii and raw recruits. But sometimes courage alone is not enough.