Chevalier is Lieutenant Nikolaus "Niki" von Preyn, a carefree Austrian officer who enjoys romancing the ladies and has recently entered into a romance with Franzi (Colbert), a charming violin player. One day, when standing as an honor guard for the visiting King of Flausenthurm and his daughter Princess Anna (Hopkins), Niki winks at his girlfriend across the street—but at that moment the royal coach passes, and Princess Anna thinks the smile and wink were for her. She quickly takes a fancy to the handsome officer, and Niki finds himself being roped into a marriage—but he hasn't forgotten Franzi.
This is a notable example of a film from The Pre-Code Era, which included much more risque humor and double entendres than films would be able to use after The Hays Code was strictly enforced a few years later.
This film exhibits the following tropes:
- Accidental Marriage: What happens to Niki.
- Artistic License Music: You can tell that Colbert isn't playing the violin she is supposed to be playing. Hopkins's piano play is pretty believable though.
- Be a Whore to Get Your Man: Franzi teaches the staid, dowdy Anna to act more slutty in order to attract Niki. ("Jazz up your lingerie!") When Niki sees Anna again after The Makeover, she's smoking and wearing sheer black lingerie. It works.
- Berate and Switch: Niki's reaction to his friend's invite to the beergarden:Niki: You're afraid to have supper with her alone. And that's why you want me along. And after supper, I go home, and you don't go home. And you think I will lend myself to such an intrigue? — Beat — Let's go.
- Berserk Button: The king of Flausenthurm is touchy about having the name of his country misspelled. He is outraged when his country's name is spelled as "Flausenturm" on a message from the emperor of Austria. Later, he makes Niki spell "Flausenthurm" before deciding that Anna can marry him.
- Bittersweet Ending: Franzi and Niki's happiness must come to an end, but Niki and Anna's marriage becomes a happy one, and Franzi can console herself with the knowledge that she did something noble by helping them.
- Bookends: Niki sings a song to the audience in the opening scene, and sings it again at the end.
- Breaking the Fourth Wall: Niki looks straight into the camera when he sings his song in the first scene and the last.
- The Casanova: In the first scene, Niki sings a song about how men in the army like to have sex with lots of women. A girl is shown entering his room. He also talks Franzi into sleeping with him on the first date.
- Distant Duet: There is one midway through with Niki and Franzi on one end and the princess in her castle on the other end.
- Eating the Eye Candy: When Niki is brought before the king and princess, the ladies of the court gawk at him. When he walks out of a burlesque show, the women follow him out. Franzi and Anna commiserate on how damn handsome he is.
- Elegant Classical Musician: Franzi plays this part.
- Girl Group: The Viennese Swallows (Franzi's all-girl orchestra).
- Hair-Contrast Duo: Franzi is a brunette and the princess a blonde.
- Love Triangle: Niki, his wife, and his girlfriend.
- The Mistress: Franzi and Niki continue dating after Niki is married.
- Morton's Fork:King: When you wink at my daughter, were your intentions honorable?
Niki: They were.
King: Then naturally you marry her.
Niki: They were dishonorable!
King: Then you HAVE to marry her!
- The Musical: There aren't any elaborate numbers with choreography, but characters break out into song several times.
- Pimped-Out Cape: The Lady-in-Waiting who comes to prepare the royal bedchamber for the wedding night has quite an amazing one.
- Royal "We": The Emperor of Austria uses this. Notably, the King of Flausenthurm doesn't.
- Ruritania: Anna's father is king of some tiny Germanic principality called Flausenthurm.
- Sexless Marriage: Niki is determined to have this after being forced into marriage with Anna. (He proposes Checkers as entertainment instead.)
- Sheltered Aristocrat: Anna.Anna: You see, I don't know very much about life. I got all my knowledge out of the royal encyclopedia. A special edition arranged for Flausenthurm—with all the interesting things left out.
- Sure, Let's Go with That: Niki decides to go along with the notion that the beautiful girl he said he looked at was actually the princess as suggested by the King. It has unfortunate repercussion though.
- TV Telephone Etiquette: Niki gets a phone call from an old friend who tells him he's engaged to the princess. He hangs up without saying goodbye.