June 1944. The Normandy landings, the largest amphibious operation in history, are already underway, and any delay could lead to German intelligence uncovering Allied plans. James Stagg, the British Chief Meteorologist, must convince the Allied command, led by General Dwight Eisenhower, to trust his unconventional methods and modify their operational plans. Scientists have only 72 hours to accurately predict two impending storms, but the fate of the entire Western Front depends on it.