I haven't seen this yet, but the topic is gripping. Andrew McLaren was involved in it, so you know it's good:
The Caravan of Mothers is an organization of brave Central American women, who embark on an epic yearly bus journey throughout Mexico in a desperate search for their sons and daughters that have disappeared on the grim journey to the United States. For the last thirteen years the Caravan of Mothers have created empowerment for these poor, indigenous peasant women that have become political and human rights activists by forming this alliance to find their loved ones.
More on the movie.
The movie's website.