What if V-E Day hadn't ended World War II in Europe? What if, instead, the Allies had to face a potent, even fanatical, postwar Nazi resistance? Such a movement, based in the fabled Alpine Redoubt, was in fact a real threat, ultimately neutralized by Germany's flagging resources and squabbling officials. But had SS Obergruppenführer Reinhard Heydrich, the notorious Man with the Iron Heart, not been assassinated in 1942, fate might have taken a different turn. In this imagined world, Nazi forces launch a guerrilla war, using the quick and dirty tactics of terrorism to overturn what seemed to be a decisive victory. Suddenly the Allies–especially the United States–are mired in a long, seemingly unwinnable conflict while battling an invisible, unrelenting enemy.