WARNING: SPOILERS

Why doesn’t “Le dernier diamant” (“The Last Diamond”) work? Why is it boring?

It’s one of those “perfect crime” movies. Simon (Yvan Attal) and his friend Albert (Jean-François Stévenin) are partners in low-level scams, but Albert hooks them up with Scylla (Antoine Basler), a skinhead-looking type, to steal a great, cursed diamond on display in Antwerp. How cursed? The woman running the Antwerp exhibition has been found dead in her car; it’s her daughter, Julia (Bérénice Bejo), who is running the show now.

That’s one of their ins. The thieves get inside information from Julia because Simon successfully woos her as “the supersecret security consultant her mother never told her about.”

Maybe that’s my problem with the movie. I went to see it for Bérénice Bejo, yet she plays a sap in it. She’s a sap in the first half, overemotional in the second, and only gets to save face (by adopting another) in the final act, as everyone bands together to scam the scammers.

Generally in a perfect-crime caper (see: this), we root for the criminals. The leaders are decent men, painstaking professionals, but one thing goes wrong and they get caught. Here? There’s Simon, who’s vaguely professional, and Albert, who’s sympathetic but a comic-relief screw-up. The others, Scylla et al., are vaguely threatening non-entities. There’s no one to root for. Other than Bérénice. Who’s play for a sap.

What do we have to believe to believe this movie?

• That Scylla needs Albert and Simon as partners.
• That Simon can successfully woo Julia.
• That Julia looks like Bérénice Bejo but is somehow dateless.
• That the thieves think the best way to get away with the diamond is for half of them to portray cops, who alert everyone to the attempted robbery, rather than simply vanishing in the night. (This is introduced to fool us, the audience, not Julia and the other folks at the exhibition.)
• That Julia’s father, Pierre (Jacques Spiesser), will still act as inside man for the thieves even though: 1) they’ve killed his wife; and 2) are scamming his daughter.
• That the woman they get to scam the scammers isn’t a policewoman but Julia wearing a rubber face mask and blonde wig; and that everyone thinks this is a good plan even though Julie has no experience in doing any of it ... and she’s wearing a rubber face mask and blonde wig.

The movie is derivative and half-hearted. Simon is kinda charming, but hardly George Clooney. Julia is ... Who is she? What’s her life like?

It’s tone-deaf, too. Because Albert screws up, an old woman with a tiny dog sits before her vanity mirror to see a giant hole in her hotel-room wall. It’s comic, but then, off-camera, she’s killed. The dog winds up with Albert. That’s comic, too—at least the audience kept laughing at the dog’s appearance—but to me he’s just a reminder that they’re all responsible for this old woman’s death. It’s as if home invaders killed Patricia and I but took Jellybean. And isn’t that sweet?

“Le derniet diamant” is supposed to be a love story, too, right? Simon winds up helping Julia retrieve the diamond, then—after some prison time—he and she live happily ever after. Or at least for an evening of banging. But would Simon have done this if Scylla hadn’t betrayed everyone by killing all but two of the thieves? And why did he leave talkative Albert alive? That’s not a thread to leave loose, exactly.

This is writer-director Eric Barbier’s fourth film but the first I’ve seen. I have no reason to see the others.