June 1944. The Normandy landings—the largest amphibious operation in history—are already in the works, and any delay risks exposing the Allies’ plans to German intelligence. James Stagg, Britain’s chief meteorologist, must convince the entire Allied high command, led by General Dwight Eisenhower, to trust his unconventional methods and change their operational plans. The scientists have only 72 hours to accurately forecast two approaching storms, yet the fate of the entire Western Front hinges on it.

Designer Jen Morrow and composer Brad Allen, who share the same phone number, have never met, but they can’t stand each other. Brad constantly keeps the line busy, playing the same tune over and over for his numerous admirers, while Jen, forced to listen to it all, is unable to make or receive calls, so she gets upset and complains to the phone company. Millionaire Jonathan Forbes is unsuccessfully courting Jen; as it happens, he is also Brad’s friend and sponsor. One day, he tells Brad about his girlfriend and the crazy guy she has to share a phone number with, and the womanizing composer realizes he’s talking about him. The description of the unfriendly woman on the other end of the line intrigues him, and when he accidentally runs into Jen at a restaurant and recognizes her voice, he decides to try to woo her by pretending to be someone else.