When a member of a drug cartel is planning on quitting and leaving the country, he’s naturally on edge. As he prepares to do a bunk, a young girl runs into his house, soon followed by a heavily armed group. Setting the house’s defence system to fortress, he assumes they have been sent by the drug lord. The real answer is much more terrifying. The assassins are looking for the girl and will do everything in their power to get her. Meanwhile, inside the house, the young son and the girl are developing a strange bond.

This Mexican action-packed shocker from Rigoberto Castañeda doesn’t pull punches with the violence, as it opens with a decapitated head rolling across the floor. This opening also gives us an inkling that there’s something about this young girl. It’s no surprise, then, when she’s revealed to be a vampire (the film’s poster makes that clear). The scenes between the two youngsters (Paulina Gil and Matías del Castillo, who are both excellent) do have a Let the Right One In quality, without being derivative. There’s also tension inside the barricade as the only bodyguard left after the initial onslaught has a beef with his boss too.

There’s an interesting story that could be continued involving the cult-like assassins that clearly have made it their life’s mission to rid the world of a vampire scourge (it would make a great comic book series). Lina, the bloodthirsty girl, is a terrifying character, particularly when in action, and is played wonderfully low key when not. Even though the surprises are telegraphed too early, Origin Unknown (Sin Origen) is an entertaining, gory action thriller that’s well worth your time.