A river in the sky - Elizabeth Peters

1910. Having brought Egypt firmly under her thumb, Amelia Peabody turns her attention to a harder challenge: Palestine, a province of the crumbling, corrupt Ottoman Empire and the Holy Land of three religions.

Hearing that Morley, an English adventurer, has raised money to mount an expedition to search for the vanished treasures of the Temple in Jerusalem, Emerson and Amelia are persuaded to go after him in order to prevent a catastrophically inept excavation and the possibility of armed protest by the infuriated members of all three religions who view the Dome of the Rock as sacred. The War Office is concerned about increasing German influence in Palestine and insists that Morley is secretly working for German intelligence. Emerson doesn't believe it, but could he be mistaken?

In the meantime, their son Ramses has been working on a dig at Samaria, north of Jerusalem, where he encounters an unusual party of travellers. One is a female German archaeologist, and the other a mysterious man of unknown nationality and unknown past. Ramses's insatiable curiosity leads him to a startling discovery about the pair. He must now pass the information on to his parents in Jerusalem - but only if he can get there alive...