III century. BC e. Two powerful states - Republican Rome and Carthage - entered into mortal combat. But victories on land are not decisive. Only the one who rules the Mediterranean will win this war. The Carthaginian fleet is strong, their naval commanders are experienced. Rome has only small ships capable of sailing in coastal waters. The Republic urgently needs to build warships and train sailors. The Roman centurion Septimius has twelve years of military service behind him, he is tempered by discipline and battles. Captain Atticus is a Greek, a second-class citizen for the Romans, and gained experience as a navigator in battles with pirates who terrified the coastal cities of the Republic. Captain Atticus spent his entire adult life in confrontation with the sea and won each time. In a naval battle off the island of Sicily, Atticus and Septimius managed to prevail over the Carthaginians. And now, by order of Rome, they have to prepare new warships and their crews for battle and prove who is rightfully worthy to bear the title of master of the seas.