The Trump administration’s “zero tolerance” policy at the border — the one that led to countless families being separated and many children left away from their parents at detention centers — deserves every ounce of our outrage. But, as the journalists working at PBS’s Frontline understand, the images of kids in cages can’t truly be explained without looking at the bigger picture of current-day life at the border. One of their recent episodes, titled “Separated: Children at the Border,” chronicles a year-long investigation into these forceful separations. Produced by Marcela Gaviria, the documentary follows correspondent Martin Smith as he guides us in answering the question on everyone’s minds: how did immigration policy in the United States reach this point?

Smith introduces us to six-year-old Meybelin, whose father fled El Salvador with her to escape violence. After crossing into America and turning themselves in to Border Patrol, the two were separated — with her father, Arnovis, deported and Meybelin held in an Arizona shelter for 33 days before being sent back to him in El Salvador. “They took me in a plane,” Meybelin says of being separated. “They said, ‘Your dad is going to come later on a plane.’ And then, when I got there and I didn’t see him… I said, ‘And my dad?’ ‘He’ll be here soon.’ And it was a lie.”

As Frontline’s report on the nearly 3,000 children separated from their parents under a Trump administration policy of criminally prosecuting adults who enter the country unlawfully shows, Meybelin and Arnovis’ story is not unique at all. In fact, This American Life’s episode “We’ll Talk About It In The Car” covered similar ground, following the story of Anita who was separated from her son at the border a month ago and who was fighting to get him back. With first person accounts of the arduous trek to make it to the border (and necessary political context that explains why people are fleeing into the US in the first place) alongside expert interviews with lawyers and government officials (including that now infamous sit-down interview with Thomas Homan, former acting ICE Director that forced him to listen to recording of children crying in those detention centers), “Separated: Children at the Border” is the kind of far-reaching and rigorously researched account of 2018 immigration crackdown as you’re likely to find.

Check out the trailer below and catch the full documentary over at PBS.org