The setting is the time of Christ. Polonius, King of Elab, is stricken with a fatal disease. He has heard about a healer in Judea called Jesus. He sends his son, Leonidas, together with Pentaurius and Dardanus to Judea to find Jesus. They arrive to find that He has been crucified. Leonidas and Dardanus return to Elab while Pentaurius remains in Jerusalem locating the Apostles and Mary, the mother of Jesus, on Pentecost eve. Mary tells him that Polonius has been cured. Pentaurius stays and hears the apostolic sermon on Pentecost. He returns to Elab with the Apostle Jude who receives license from Polonius to teach about Jesus only to the Graeco-Elabites who, for the most part, worship the Greek pantheon. The Old Elabites practice a form of Judaism and the religious leaders do not want them to abandon their traditional faith. Eventually, the Old Elabite hierarchy under the leadership of the High Priest, Rua, succeed in getting Jude banished from Elab.

Diocles, Polonius’ other son and Leonidas’ half-brother, conspires with the King of Parthia to overrun the Elabite trading outpost at Kadimah (modern Kuwait) using Arab surrogates. Diocles never enjoyed favor with Polonius partly because his mother was a daughter of Herod the Great, an Idumaean by birth, Idumaeans were outcasts in Elabite society. Idumaea bordered Elab on the north. Idumaeans were common laborers and household servants. Leonidas has a Roman mother. Elab is bound by treaty to Rome that hands it over to Caesar if the reigning monarch dies without an heir. Diocles has been unable to produce children. Leonidas has a son through an unhappy marriage with a Roman wife.

Leonidas and Pentaurius lead a naval expedition into the Persian Gulf where they are ambushed by a Parthian fleet. Leonidas is killed and Pentaurius is rescued by Vashtar, a Parthian and boyhood friend. . While in Parthia, Pentaurius meets and marries Basemath, an Elabite girl taken captive at Kadimah. She was converted to Christianity by Jude and another Apostle, Simon, now preaching in Parthia. After bringing Jude to the attention of the Parthian King through a series of spiritual combats with pagan priests, the king frees Pentaurius and the surviving Elabite prisoners-of-war. They return to Elab via Kadimah and kidnap Tryphon, the former Elabite governor of Kadimah, who had plotted with Diocles to betray the outpost. Tryphon confesses to Polonius who exiles Diocles to Arabia.

Polonius’ grandson (Leonidas’ son) drowns leaving Elab without an heir. Achillas, Pentaurius’ father and court physician, discovers a loophole in the treaty that allows Polonius to adopt an heir. He adopts Pentaurius. En route to Rome to secure the approval of Emperor Tiberius, Pentaurius visits Mary in Jerusalem. She tells him that Elab has a destiny to save the East from a threat that will someday emerge out of Arabia; however, this destiny hinges on Pentaurius’ choice of a successor.

Polonius dies, Pentaurius becomes King and Diocles escapes from Arabia. Diocles enlists the aid of the new Emperor, Caligula, who sends an army to invade Elab. Pentaurius defeats this army through a series of clever deceptions and captures a young general, Vespasian, who vows to annihilate Elab and erase it from history. Pentaurius releases Vespasian and the other surviving Romans. Caligula executes Diocles and is himself assassinated. Pentaurius forges another treaty with the new Emperor, Claudius.

Christianity takes hold in Elab under the Apostle Thomas causing Rua to incite a civil war. Pentaurius takes the field against him and is captured, together with Thomas, by the rebels during a sudden and mysterious deluge. Penataurius and Thomas are on the verge of being executed when three suns (representing the Trinity) appear in the sky ending the downpour. The ground is completely dry and the mud and grime disappear from everyone’s clothing. After a few minutes the sun resumes its normal appearance. Thomas preaches to the rebel soldiers and nearly all of them come over to Christianity. Rua and some fanatics retreat into the desert where a caravan finds their remains torn to pieces by a a pack of wild dogs.

Twenty years pass. Pentaurius’ son, Nepulon, seizes power and allies himself with Judea in its revolt against Rome. He is killed or disappears in battle in Judea. Pentaurius is restored to power but is later forced to abdicate by Vespasian, now Roman Emperor, who promises to rescind his oath to destroy Elab if Pentaurius will go into exile. Pentaurius retires to Jeddah in Arabia. Two years later Vespasian unleashes his legions upon Elab leveling its cities and towns, exterminating the population except for a few who escape into Arabia and erases all references to Elab from Roman records. Pentaurius writes his memoir and buries it in the hills between Jeddah and Mecca where it will be found in the late 20^th Century in an event detailed in the beginning of the novel.