When you have a good setup a movie plot doesn't have to be more complicated than this.
A man is travelling through the Spanish countryside and stops for some gas. He meets a young lady in the men’s room, they have sex (happens all the time) and after the deed is done she steals his wallet, though she is kind enough to pay for his gas. He continues on his journey into the wilderness and spots a glint of something on a mountaintop and moments later a shot is fired. Before you can say the word sniper he is stranded with no car, a bullet wound to the leg and running for his life together with the young woman he met earlier. They have no idea who is after them but the assailants have no qualms over putting a bullet in the head of a policeman.
This is a grade A thriller, filled to the brim with gruesome suspense of the best kind. It is a simple concept that works perfectly and you find yourself holding your breath listening for that whistling sound of a bullet an instant away from hitting a tree, a chest or a head. The excellent acting adds a lot to this, although our hero is blessed with a bit of a cowardly streak which makes it hard to like him at times. It causes a bit of frustration but in the end I think the movie is helped by it, increasing the nastiness even further. We are even treated to that old plot device "the twist" but refreshingly enough this happens some 20-25 minutes before the end when we all of a sudden are allowed to see the rest of the movie through the eyes of the shooters, something that does lower the tension slightly but works really well. This is a perfect example of what the Spanish does best; hard-hitting, nasty thrillers and I give it my highest recommendation.