It is, yes, an adaptation of the popular French literary character Arsène Lupin, gentleman thief, and specifically a 1907 play. John Barrymore is the Duke of Chamerace, a French nobleman who may or may not be Arsène Lupin, but who is definitely deep in debt. Lionel Barrymore is Detective Guerchard of the French police, who is certain that Chamerace is indeed Lupin. The case of Lupin has become a major scandal in France and Guerchard's boss has demanded that he catch Lupin in a week or he's fired.
A dim-witted war profiteer named Gourney-Martin not only doesn't think that Chamerace is Lupin, he has even invited Chamerace to his country estate to make sure that Arsène Lupin doesn't rob it. Before going off on vacation the duke holds a lavish party at his (heavily mortgaged) mansion. There he meets a lovely White Russian countess named Sonia (Karen Morley). They hit it off and Chamerace invites Sonia to go to the country with him. What Lupin doesn't know is that Sonia is a police plant, sent by Guerchard.
First of five films the Barrymore brothers made together, others of which include Dinner at Eight (where they don't share any scenes) and Best Picture winner Grand Hotel. Compare 2004 French film Arsene Lupin.
- Artistic License History: Chamerace hides the rolled-up "Mona Lisa" in an umbrella. The real "Mona Lisa" was painted on wood.
- Asshole Victim: Gourney-Martin is a war profiteer who made a fortune selling arms during World War I.
- Chekhov's Gunman: Guerchard's daughter, who pops up in one random scene. Later she becomes important when Lupin has her kidnapped as a bargaining chip to force Guerchard to let him go.
- Dramatic Irony: Guerchard, trying to get Chamerace to reveal where the "Mona Lisa" is hidden, bangs the duke's umbrella on the table and says "I'll find that picture if I have to tear this place down stone by stone!" The painting is wrapped up inside the umbrella that Guerchard is banging.
- Gentleman Thief: The Duke of Chamerace, a French nobleman living the high life as Arsène Lupin, generally stealing only from rich creeps.
- Getting Crap Past the Radar: Loads of this, as this is a film from The Pre-Code Era. When the bank guys try to foreclose on the house, Chamerace says they can stay there while he goes away, then he grins sneakily and says "And I'll give you a couple of good telephone numbers." (For High Class Call Girls, presumably.) Later when he sees Sonia playing solitaire, the duke says "Do you want to go back to your solitaire, or would you prefer something that requires two people?"
- Ham-to-Ham Combat: A lot of this between the Barrymores, especially in the climactic scene where Guerchard is demanding that Chamerace give up the painting while Chamerace is demanding the release of his men.
- Have a Gay Old Time: When Guerchard first arrests Chamerace at Gourney-Martin's house, he says "This is the end of the gay life for you!"
- Hero Antagonist: Guerchard, the police detective trying to catch a thief.
- High-HeelFace Turn: Inverted. Sonia, deputized by the police to worm her way into Lupin's confidence, falls in love with him. She lies to give him an alibi when Guerchard shows up to make the arrest.
- Idiot Ball: Gourney-Martin is quite the moron, not only inviting Chamerace to his home after Guerchard has accused Chamerace of being Arsène Lupin, but even showing Chamerace how to disarm the special electrified safe.
- Impoverished Patrician: Chamerace, it seems, given that he has to step away from his party to meet two guys from the bank who want to repossess his house.
- Let Off by the Detective: Guerchard has finally arrested Chamerace and is taking him to the station. As their car trundles over a bridge Guerchard casually mentions that he lost a man off that bridge once, when the man leapt out of the car and jumped off the bridge. Guerchard further mentions that he shot at the man but missed because he's "a bad shot", and then inquires if Chamerace can swim—Chamerace is a good swimmer. Chamerace leaps off the bridge and escapes.
- Meet Cute: Chamerace goes into his bedroom to find Sonia naked under the sheets. It turns out that the strap on her dress broke and a maid is mending it in the side room. (In reality it's a charade arranged by Guerchard to get Chamerace and Sonia together.)
- The Mole: Sonia is a forger who was paroled by the police for the specific purpose of using her beauty and charm to get in the company of the Duke of Chamerace.
- Phantom Thief: The literary Lupin was the Trope Maker for Phantom Thief, and the trope plays out in this movie, with Lupin signing his name at his robberies and writing "tut tut" on a fake "Mona Lisa" that Guerchard put out to trick him.
- Sexy Backless Outfit: How Sonia is always dressed for parties.
- Sleepwalking: Sonia is particularly obvious about this, doing a very lame sleepwalking routine as a means of getting into Chamerace's room. Chamerace catches on, of course, and pours a bucket of water over her head.
- Soft Water: That's an extremely high bridge that Chamerace dives off of.