Warner Bros. held a test screening on Tuesday for director Chris Peckover’s sure to be controversial thriller Undocumented. I was fortunate enough to be in attendance and, while I can’t discuss the film at length (it’s still a work-in-progress), I will say this: Peckover is one sick bastard … and that’s good news for horror fans.

OK … I’ll say a little more.

Undocumented follows a group of young filmmakers, led by producer Liz (Alona Tal) and director Travis (Scott Mechlowicz), as they document the hardships faced by Mexican immigrants living illegally in the United States. Fueled by ambition and fist-pumping ideals, they collect hard luck stories from poor, undocumented workers and set out to expose their abusive American employers. Things go terribly wrong, however, when they decide to travel into Mexico to film a group of immigrants as they cross the border into New Mexico with the help of a “coyote.”

(Update: To see photos from the movie, click here)

Ambushed by a group of vigilante “patriots,” the filmmakers are taken hostage and then forced to document the torture and murder of the captured immigrants. The patriots are as zealous as they are cruel and have a very specific purpose in mind for the footage being shot.

The torture scenes, though not overly graphic, are intense and emotionally jarring. Unlike the Saw films—where it’s fun to watch Jigsaw’s victims get maimed and slaughtered in creative ways—Undocumented is one of those rare horror flicks that makes you care about the characters, which in turn makes their torment almost unbearable (yea, I said almost).

The actors, lead and supporting, really drive the drama home. Yancey Arias turns in an especially devastating performance as Alberto, a goofy and well-intentioned husband/father trying to keep his family safe.

Undocumented also benefits from a taut script written by Peckover and Joe Peterson. The dialogue is so good in this movie—not in a Tarantino showoff-y kind of way, but in a very authentic manner. From the patriots’ hate speak to the tension-filled exchanges between Travis and Liz (they share a romantic past) to the playful ribbing between camera man (Greg Serano) and boom guy (Kevin Weisman)—every conversation and reaction is believable and engaging. And, the humor is especially wicked and sometimes highly inappropriate (did I just laugh at a condom joke during a vicious torture bit? WTF is wrong with me?).

A couple of additional notes:

Despite its docu-drama angle, the film never lingers too long during its shaky-cam and infrared moments, making the technique all the more effective (yea, I’m looking at you Oren Peli).

And, finally, I regret to inform you all that Alona Tal (”Supernatural”) does not appear nude in the film.