Lily is in love, but with a man she has never seen. She and Erich both work as switchboard operators, she in Paris, he in Berlin. They talk to each other every day and now they are hopelessly in love. Finally, they decide to meet up in Paris. Lily has a photograph of Erich and so is surprised when the man who meets her at the station looks nothing like the man she had been expecting. Not realising that the man is an impostor, Lily allows herself to be courted by him. Meanwhile, Erich has mistaken another woman, Annette, for Lily, and ends up seeing far more than he expected to on a first date. The weekend adventure over, Lily and Erich return to their humdrum lives, only to be dismissed by their employers for their unorthodox method of cementing Franco-German relations over the phone. Just when all seems lost, Fate conspires to bring the two young lovers together...