À la fête de Lesaca, petit village du Pays Basque espagnol, se produisent le chanteur Vincent Etchebar et son fidèle ami trompettiste Bilou. L'impresario parisien Cartoni remarque Vincent et souhaite l'engager. Au même moment, le ténor Miguel Morano, refuse de partir pour le Mexique avec la vedette féminine Eva Marchal, de peur de retrouver Tornada, une furie à qui il a autrefois promis le mariage. Alors que Vincent et Bilou sont montés à Paris, Cartoni les recherche désespérément. Vincent sosie de Morano, remplacera sa vedette dans le rôle titre de l'opérette Le Chanteur de Mexico, sans se douter qu'il existe un vrai Miguel Morano. Mais les deux compères restent introuvables. Ils sont devenus peintres en bâtiment sur la Tour Eiffel, et logent dans le même immeuble que Cricri, une pétillante jeune fille. Grâce à un concours radiophonique, auquel il s'est inscrit sur l'insistance de Cricri, Cartoni l'entend et le convoque. Vincent est engagé et est présenté à sa partenaire. Eva s'éprend de lui et le fait répéter en privé chez elle. Quant à Vincent, entre elle et Cricri, son cœur balance. L'équipe part pour le Mexique. Dès son arrivée à Acapulco, Vincent, sous le pseudonyme de Miguel Morano, est repéré par Tornada qui réussit à le faire enlever. Mais Bilou, Cricri et Cartoni arrivent à temps pour expliquer la méprise. Alors que Cricri et Vincent s'avouent leur amour et que Bilou tente de réconforter Tornada, la tournée se termine dans la capitale Mexico.
Young Prince Karl, of a small sub-kingdom of the German Empire, is sent off near the turn of the 20th century to get a university education in Heidelberg, Baden-Wuerttemberg. His grandfather was one of a handful of petty kings within German-speaking central Europe. Fictional Karlsburg is small, but fiercely proud of its history and traditions.
Rose Marie Lemaître (Ann Blyth) rencontre Mike Malone (Howard Keel), policier canadien qui tente de l'utiliser afin de capturer James Duvall (Fernando Lamas), trappeur recherché, et amant de la jeune femme.
The young widow Crystal Radek is invited to Marshovia, a small European kingdom, to attend the unveiling of a statue in honour of her deceased husband. The royal coffers are seriously in need of her money so the king sends out count Danilo to seduce her.
Marie de Flor (Jeanette MacDonald) is a Canadian soprano performing in Roméo et Juliette in Montreal; the Premier of Quebec is in the audience. Inviting him and his entourage to supper after the performance, she learns from a 'half-breed' man called Boniface (George Regas), that her brother Jack, supposedly in prison for armed robbery, was wounded as he escaped from prison and has killed a Mountie in the process. Making her excuses, she leaves for the Canadian wilderness with Boniface, hoping to help Jack.
During the 18th century in New Orleans, Louisiana, a French nobleman in disguise as a bondsman, Charles (Nelson Eddy) leads his fellow bondsman in revolt against his ship's captain, commandeering the ship and heading out to sea.
Set in late 19th century Vienna, the story focuses on the romance between music teacher Carl Linden (Nelson Eddy) and his prize pupil Sarah Milick (Jeanette MacDonald).
To avoid an arranged marriage to Don Carlos, an elderly Spanish duke, Princess Marie masquerades as her uncle's former servant, Marietta, and escapes from France on a ship with casquette girls who are traveling to New Orleans to marry colonists. On board, Marietta befriends Julie.
The original plot is more-or-less adhered to, with some significant alterations. Benny is depicted as a comic Bob Hope-like coward, but not as a sissy. El Khobar's alter ego is that of a mild-mannered (but not squeamish) Latin tutor and anthropologist, whom Birabeau (Ray Collins) hires to keep Margot (Kathryn Grayson) from flirting with his regiment.
Playboy, Captain Danilo (Maurice Chevalier), is ordered by King Achmet of Marshovia (George Barbier) to court and marry Madame Sonia (Jeanette MacDonald), a rich widow who owns a large portion of the kingdom.
Secret agent Nina Maria Azara (Jeanette MacDonald) is working undercover for the King of Spain (Tom Rutherford) as a singer known as the "Mosca del Fuego" or "Firefly." Despite her love for Captain Andre (Allan Jones), she tricks him so that his general will change the French defensive positions, thus allowing the Duke of Wellington to win the Battle of Vitoria. In the end Nina and Andre leave together for a new life in peace.
Prince Danilo falls in love with dancer Sally O'Hara. His uncle, King Nikita I of Monteblanco forbids the marriage because she is a commoner. Thinking she has been jilted by her prince, Sally marries old, lecherous Baron Sadoja, whose wealth has kept the kingdom afloat. When he dies suddenly, Sally must be wooed all over again by Danilo.
Denise, alias « Nitouche », est sortie par ses parents du couvent pour la marier. Au cours de diverses péripéties, elle va jouer au music-hall, se retrouver en uniforme de dragon, pour finalement tomber amoureuse de la personne qui lui était destinée par sa famille.
Ciboulette, une petite maraîchère des Halles, rencontre Antonin, un riche fêtard. Il s'éprend de Ciboulette mais retourne à son ancienne, et volage, maîtresse. Un compositeur lance Ciboulette qui devient une grande cantatrice et réunit ainsi les amoureux.