June 1944. The Normandy landings, the largest seaborne invasion in history, have already been prepared, and any delay risks German intelligence uncovering the Allies' plans. Britain's chief meteorologist, James Stagg, must persuade the entire Allied command under General Dwight D. Eisenhower to trust his unorthodox methods and alter the operation plans. There are only 72 hours left for scientists to provide the precise forecast for two approaching storms, but the fate of the entire Western Front depends on it.