In December 1943 with the rising realization that the Allies are planning to invade Fortress Europe, Field Marshal Erwin Rommel is assigned the title of General Inspector for the Atlantic Wall. His mission is to assess their readiness.

What he finds disgusts him. The famed Atlantikwall is nothing but a paper tiger, woefully unprepared for the forces being massed across the English Channel. His task--to turn back the Allied invasion--already seems hopeless.

His superior, theater commander, crusty old Field Marshal Gerd von Rundstedt, who had led the Reich to victory in the early years of the war, is now fed up with the whole Nazi regime. He lives comfortably in a plush villa in a quiet Paris suburb, waiting for the inevitable Allied invasion that will bring about their final defeat.

General der Artillerie Erich Marcks, badly injured in Russia, is the corps commander on the ground in Normandy, trying to build up the coastal defenses with woefully inadequate supplies and a shortage of men to fulfill Rommel's demands. Marcks is convinced that the Allies will land in his sector, but no one higher up the chain of command seems interested in what he thinks.

Meanwhile, aristocratic Generaloberst Hans von Salmuth, an outspoken, cocky, experienced veteran of the Russian Front, has been given responsibility for defending Fifteenth Army's coastline at Calais--the area that the High Command thinks is most likely to be the Allies' objective. General der Panzertruppen Geyr von Schweppenburg is preparing the lite panzer divisions for what may lie ahead. Generalmajor Max Pemsel struggles in coordinating efforts to prepare Seventh Army, suspecting that if an invasion comes he will be the hub of the German response. All of the Western Theater commanders are subject to the whims of Adolf Hitler, hundreds of miles away but continually issuing orders increasingly divorced from the reality of the war.

Countdown to D-Day takes a detailed day-to-day journal approach tracing the daily activities and machinations of the German High Command as they try to prepare for the Allied invasion.