In February 2020, Washington Post reporter Arelis R. Hernández walked across the bridge from Brownsville, Tex., to Matamoros, Mexico, two sister cities along the international border with the glistening green Rio Grande snaking between them. Up on the levee, a breathtaking sight unfolded before her: a makeshift migrant camp full of thousands of asylum seekers from all over Latin America forced by the Trump administration to wait in Mexico while they plead their cases.There in the camp, Hernández met a woman from El Salvador named Nancy and her two teenage children. Nancy had a chilling story to tell about how she wound up there — and why she feared she would never get out. In this special two-part series, Hernández and producer Ted Muldoon explore what Nancy’s story reveals about the real-world impact of the Trump administration's "Remain in Mexico" policy.In Part 1, Nancy slowly unspools her story, starting with her journey north. After she and her children make their way across the Rio Grande, they're intercepted — not by Border Patrol, but by the cartels. To find photos and videos of Nancy’s journey and her life in the camp, visit wapo.st/nancy.Read more:Photographer Michael Robinson Chavez and reporter Mary Beth Sheridan capture haunting images of migrants fighting for survival at the border. Reporter Kevin Sieff looks at what happens when asylum seekers miss their court dates because they were kidnapped.