The unfortunately-named Quim (Sbaraglia) is driving through a remote region of Spain, when he encounters the mysterious Bea (Valverde) at a rest-stop. One quick bonk later, they part, only for Quim to realize his wallet is also missing. He sees her car turning up into the mountains and follows, only to find someone firing at both him and his car. He high-tails it out of there on foot, only to find Bea, whose tyre has just been shot out, apparently by the same sniper. With no way to call for help, the two have to try and make their way out of the mountains, while being followed by their unseen assailants. Even when they manage to link up with a couple of policemen and things look brighter, it proves to be only a momentary respite, and it becomes clear that, whoever is behind their situation knows the territory well and has no intention of letting anyone off the mountain alive.
Eventually, the source is revealed, and there's some interesting use of first-person shooter styled cinematography which hint at a possible cause behind the violence [though the director has supposely denied it's supposed to be critical of video-games]. The film carefully doesn't explain everything - Quim appears to take out a hunter early on, and it's never explained quite who that is - yet there's enough to avoid accusations of lazy scripting. The revelation in the middle is not quite as shocking as it might be; my first thought was to start listing films that have gone similar routes. However, the film recovers, for a rousing finale in an abandoned village - which looks like it might be a level from Call of Duty or similar. There isn't much time for characterization, with a storyline that's primarily driven by the action; this may be wise, since some of Quim's early actions had Chris doing some sniping at him of her own, albeit verbal rather than armorial. Still, as a taut thriller, it's effective enough, with a cinematic fat percentage in the low single-figures.