Summer 1944: Yugoslavia is locked in a war within a war. In addition to fighting the German occupation, warring factions battle each other. Hundreds of Allied airmen have been shot down over this volatile region, among them American lieutenant Bill Bogdonavich. Though grateful to the locals who are risking their lives to shelter and protect him from German troops, Bogdonavich dreams of the impossible: escape.  
 
With three failed air missions behind him, Lieutenant Drew Carlton is desperate for redemption. From a Texas airbase he volunteers for a secretive and dangerous assignment, codenamed Operation Halyard, that will bring together American special operations officers, airmen, and local guerilla fighters in Yugoslavia’s green hills. This daring plan—to evacuate hundreds of stranded airmen while avoiding detection by the Germans—faces overwhelming odds. What follows is one of the greatest stories of World War II heroism, an elaborate rescue that required astonishing courage, sacrifice, and resilience.