CNN's Nick Paton Walsh walks with migrants attempting to cross the Darien Gap, a perilous jungle crossing between Colombia and Panama, as they head north to seek asylum in the United States. "The Trek: A Migrant Trail to America" premieres on April 16 at 8 p.m. ET/PT on CNN's new Sunday primetime series, "The Whole Story with Anderson Cooper". #migrants #dariengap #asylum