The principality of Lucca is bankrupt because the natives spend all their time making music, not money. So Austria threatens to invade. (that Austria is mentioned by name is significant too on other levels). So Lucca goes for Lucre and music is banned. Lucca's Economic Miracle attracts International Attention, so a reporter from New York arrives. Jimmy Durante's trademark proboscis looks even funnier when he's wearing early 18th costume. "My giant trunk!" he says, meaning his luggage. Durante's character "Whistler" (pun) pronounces Lucca as "Luck-AH" and mangles local names. But he's no buffoon. He's incensed by repression and supports the locals who want music, even though he's not a musician himself.
Richard Tauber is opera singer Mario Carlini, Lucca's Greatest Export, feted in Vienna. But when he comes home, he's threatened with prison. So concerts have to be organized in secret, through the underground. "There's Revolution in the air!" Even the military are upset. "How can we march without marches?". So Tauber heads a procession of trumpeters, fiddlers and singers who march on the palace. "Let's make music a national industry!" So the Princess (played by Tauber's wife, Diana Napier) reverses the anti-music decree. As if it were so easy in real life. The little opera house opens again and Tauber sings an aria. It's in English, but the sound's so bad and his diction is kaput, so you can't make out the words, but who cares? He does it with a flourish.
Forbidden Music is pretty hammy, certainly not "great art" and no-one had illusions. But as a parable it's a lot sharper than it seems. It was directed by Walter Forde with music by Oscar Straus (one "s"). Enjoy it here: