It is 48 BC and Caesar is master of Rome, but Pompey is at large in the huge recruiting grounds of the east with a core of powerful officers, nominally representing the senate in absentia. As the general deals with matters in the city his army gathers at the coast, waiting to cross the sea and fight that worst of all conflicts: civil war. This will be no easy campaign for Caesar and his officers. Fronto and Galronus, both preparing to join the campaign, know that they will face appalling odds right from the outset, for Pompey's immense navy controls the seas, and the force he has gathered in the east will dwarf that of Caesar, commanded by shrewd officers like the great Scipio and the turncoat Labienus. From the bitter Adriatic Sea to the mountains and valleys of the Balkans, Fronto and his men strive to stop Pompey and bring the war to an end, heading for a conflict the likes of which none have ever seen. Hades awaits the legions of Rome on the plains of Pharsalus.

The war in Africa is over and the rebel cause hangs by a thread. With opposition to Caesar now led by Labienus and by Pompey’s sons in Hispania, Caesar is one step from ending the civil war that has plagued Rome for years. Before the war can be pursued, though, Caesar has matters to attend to in Rome. And against a backdrop of glorious triumphs and civil friction, the general’s old warhorse Marcus Falerius Fronto begins to uncover a series of events that may have a cause in common. Investigation, however, is sidelined as necessity finally draws everyone across the sea to the crucible of war once again. In Hispania the clouds gather, for though the rebels may have been pushed into a corner, they are far from beaten. With the great name of Pompey and the tactical genius of Labienus on their side, Caesar must fight hard to win the day. Fronto and his friends must give all they have now, for the prize for this campaign is the ultimate one: the republic itself.

It is 58 B.C. and the mighty Tenth Legion, camped in Northern Italy, prepares for the arrival of the most notorious general in Roman history: Julius Caesar. Marcus Falerius Fronto, commander of the Tenth is a career soldier and long-time companion of Caesar's. Despite his desire for the simplicity of the military life, he cannot help but be drawn into intrigue and politics as Caesar engineers a motive to invade the lands of Gaul. Fronto is about to discover that politics can be as dangerous as battle, that old enemies can be trusted more than new friends, and that standing close to such a shining figure as Caesar, the most ethical of men risk being burned.

The Danubian frontier is weaker than ever, and a storm is gathering in the north . . . Deep winter, 376 AD: Emperor Valens has withdrawn the field armies from Moesia and Thracia to fight in the Persian War. The impoverished limitanei legions left behind to defend the banks of the River Danubius are now all that stand between the war-hungry Goths and heart of the Eastern Roman Empire. For Numerius Vitellius Pavo and the men of the XI Claudia, the brief from Emperor Valens is simple: to avoid war with the Goths at all costs while the Roman defences are so weak. But in the frozen lands north of the Danubius a dark legend, thought long dead, has risen again. The name is on the lips of every warrior in Gutthiuda; the one who will unite the tribes, the one whose armies will march upon the empire, the one who will bathe in Roman blood . . . The Viper!

The war in Gaul is over, but the fight for Rome is only just beginning. Denied his consulship by the senate and nearing the end of his term as governor, Caesar waits at Ravenna with one legion, making a last attempt at reconciliation. Threatened with prosecution if he returns to Rome, just one path is becoming clear: war against the senate. Fronto and Galronus are bound to the service of the Proconsul, facing a war against other Romans, and able neither to prevent nor avoid it. Caesar’s path to safety will take them the length of Italy, and to familiar old lands in southern Gaul and Spain, where their friends and family now wait, believing themselves safe from hostilities. With a new officer stirring up trouble, Pompey and the senate defying them, a father-in-law busily incriminating himself and powerful Roman generals consolidating positions against them, Fronto and his friend are bound for that worst of all conflicts: Civil War.