In 1916 Captain Melchior von Fuchsheim is abruptly transferred from the horror of the trenches to a remote outpost in the Austrian Alps. There he is instructed to build an impregnable fortress beneath the massive Ortler Glacier, where the Austrians are locked in a stalemate against the Italians while battling nature's cruelest extremes of cold and altitude. But Major Stutz sees Melchior as a charlatan, and a struggle erupts as Melchior fights to defend the Jewish conscripts under his command, deep in the tunnels and caverns of the Eisfestung, the Citadel of Ice.