Siege of Heaven

British author Harper brings to life the political and religious passions of the 11th-century in his excellent conclusion to his First Crusade trilogy (after The Mosaic of Shadows and Knights of the Cross). While series hero Demetrios Askiates, a Greek in service to the Byzantine emperor, doesn’t have a mystery to solve as he did in the previous two books, Harper’s gifts as a writer are more than equal to the task of sustaining interest and suspense without that plot device. As various warlords compete to be the first to reach Jerusalem, Askiates attempts to free himself of his obligations to the emperor and return home to Constantinople. A diplomatic mission to gain the ruling Fatimids as allies against the Turks sends Askiates to Egypt instead, where he must endure a harrowing trek through the desert to survive. This first-rate historical makes accessible the prosaic details of everyday life in a distant era. (Dec.)