In the midst of World War II, a Jewish shopkeeper named Jakob (Robin Williams), is sent to ghetto headquarters for breaking curfew. While at headquarters he overhears a broadcast on the radio that tells of Russian troops and their movements. Upon returning to the ghetto, Jakob slowly disseminates this information, and then continues to make up more stories from his 'secret radio' as he sees the hope that this brings to the people. But Jakob has another lie that he is desperately hiding from the Germans, that he is hiding young Lina (Hannah Taylor Gordon), who escaped from a German transport train. When word of the 'secret radio' reaches the Germans, though, they begin a thorough search of the ghetto to try and discover it.