I've been sort of convinced for years now that all the best B action movies are coming from France. Even the English language ones are all produced by Luc Besson. This one is actually the first French action movie I've come across that didn't have Besson's name attached to it, and it was made in 2002, but I'd never heard of it...which is basically the problem with French action movies. No matter how awesome, buzz does not exist. I only watched this one because Netflix randomly recommended it, and it could be instaqueued.
Which is a shame, because this was tight as hell. The set up takes its time letting you work out what's going on without telling you directly, so even describing the basic concept sort of results in the opening of the movie being less an intriguing mystery and more a puzzling get-to-the-point exercise, but roughly speaking, five criminals (including a parkour dude) take two security guards hostage so they can loot a shipment of laptops. Meanwhile, police escorting the head of an Albanian organized crime syndicate are ambushed; all but three of them are killed. They take refuge...inside the warehouse the criminals are robbing. All of them end up joining forces to try and withstand the siege.
The script is a lean, mean, efficient machine, never letting tension ease for a fucking second; the characterization and emotional moments are all serving two points -- if there's an intensely emotional moment, odds are it's also giving us a key piece of information, serving to move the plot forward, or distracting us from realizing what's about to happen next. It definitely doesn't have any intention of being anything more than a hella intense action-thriller, but the sheer purity of that purpose makes it immensely satisfying to watch.