The debate over border policy in the United States has reached levels of nonsense worthy of Lewis Carroll. On the right, you have presidential candidate Donald Trump tarring all immigrants from south of the Rio Grande as "rapists and murderers," and pledging to build a "huge" wall to keep them out. On the left, you have Democrats so high on the warm and fuzzy feeling of "embracing diversity" that they imagine an open-border policy of uncontrolled immigration is sustainable. (Hey, EU! How did that work out for you?)

While coastal-state liberals assume that illegals are all like that nice Honduran boy who mows their lawn, border-state Tea Partiers think they're all MS-13 or Zeta gangbangers. Really, though, it can never be one or the other — an open border is indiscriminating, letting in both the good and the bad. The question lingers: Is America really being infiltrated by Mexico's ultra-violent drug cartels, or have we all been watching too much "Breaking Bad"?

Into this mess comes "Cartel Land," a chilling documentary that challenges glib ideological beliefs and forces people to confront the complexity of the situation. Director Matthew Heineman follows a "concerned citizen" named Tim "Nailer" Foley, a rugged and bitter army veteran who formed his own militia-style group to patrol the Arizona border with Mexico.