The Secret of Etemenanki is comparable to Treasure Island, Raiders of the Lost Arc, or the Temple of Solomon.  It also has some elements of Ivanhoe.  It is a story of competing interests set in a time of war.  

 In 409 AD the Visigoths are invading the Roman Empire. To protect the Empire, the Emperor Honorius sends the Imperial treasure out of Ravenna ahead of the invading Visigoth Army.  Entrusted to the Centurion Achatius Licinius Geta, the treasure is taken to Ostia where it is shipped out of the empire and lost.  

The book changes scenes to 1187 and the battle of Hattin.  Saladin has crushed the Christian Army of Jerusalem.   Left behind on the battle field, Sir Byron Fitzwalter is alone among the dead.  Fleeing to the Sea of Galilee, he is found by Father Villhardain.  

Father Villhardain is no ordinary priest.  Rome has learned of the lost treasure and in an effort to finance the crusades, the Holy Father, Urban III, has sent Father Villhardain and his assistant, Brother Carl to find Rome’s missing treasure.    Father Villhardain has learned the treasure’s location but there is a problem, the treasure is deep in Saracen territory.

Saladin knows Rome is seeking the treasure.  He knows that if the Church finds the treasure, the war to retake Jerusalem might fail.  He sends his most trusted knight, along with 80 battle hardened warriors, to find the priest and capture him.  The race is on as the Christians travel down the Euphrates to find Babylon, to find the treasure and bring it back to Rome before Jerusalem falls to Saladin.

Who will win?  What are the consequences for the war for Jerusalem?