Border Patrol Agents William Ortiz and Eduardo Berlanga intercept a pickup truck packed with people who have illegally crossed the border. The situation heats up when they find two young twin girls and a distrustful father.

Aviation Enforcement Pilot John Manheimer and his Black Hawk team patrol the Sonoran Desert searching for illegal border crossers and drug smugglers. After an unmanned aerial vehicle spots suspected illegal border crossers in the mountains, Aviation Enforcement Officer Oscar Peru and his crew deploy to round them up in the rugged terrain. From a remote border patrol station, teams of five agents do seven-day rotations and are on call 24/7.

Officer Hector Navarro stops a silver pickup truck at the Nogales port of entry. When suspicion prompts a canine sniff for narcotics a cleverly hidden trove of heroin is uncovered - breaking an all-time record for drug busts at this port of entry.

National Geographic goes inside the US-Mexico border with unprecedented access to the growing arsenal of high tech cameras, ground radar, and skilled trackers who are faced with the challenge of controlling the desert every day.

A young man drowns trying to cross the Rio Grande, and agents must now identify him and return his body to his family. Agents and officers target a human smuggling operation and raid a safe house containing more than 20 illegal immigrants living in cramped, unsuitable conditions. And, inspection of a bell pepper shipment finds tiny invasive snails that could destroy thousands of acres of cropland if introduced into the U.S.

An 18-wheeler carrying more than 1,000 pounds of concealed marijuana is discovered by a rookie agent and his canine partner. A group of illegal crossers takes agents on a four-hour chase after setting off sensors, and it requires the help of local ranchers and a thermal imaging camera to catch them. An Ecuadorian woman and her young daughter — injured, dehydrated and famished — are rescued from the harsh terrain after being abandoned by smugglers, and face deportation unless the mother can prove they have reason to fear for their lives back home.