Officers examine a trailer filled with cooking supplies and unearth a GPS tracker -- the kind cartels use to watch their loads. US citizens who accidentally approach the international border are inspected, and it turns out they have a few secrets.

When a trailer full of sea salt shows up at the bridge, officers decide to inspect it; the bags do contain a crystalline substance and it's an illicit one; during an inspection of a U.S. citizen, something illegal rolls out of his pocket.

When a drug dog alerts a vehicle full of clubbers heading to a techno bar, officers find the group has gotten creative with their illicit drugs; officers inspecting a couple's truck find bags full of rat carcasses to be used in a specialty soup.

When officers see an approaching vehicle make a sudden U-turn, they give chase and find a bag with a gun and ammunition; tourists arrive with a large amount of Botox and dermal fillers, hinting they may be planning to perform cosmetic treatments for cash.

When two sisters are pulled over for making an unsafe lane change, officers discover they have an illicit stash that can't cross the border; a Mexican couple attempts to bring a bag of foul-smelling insects for a special recipe.

When a bus is stopped for a routine search, an X-ray reveals some contents may be under pressure; a U.S. family's pet parakeet is denied entry into Mexico and without special USDA approval, it may not be allowed back into America either.

When a man waiting in the pedestrian line to enter the U.S. suddenly turns and sprints back toward Mexico, officers give chase; a Mexican national seeks asylum in the U.S. after claiming he was kidnapped and extorted for information by cartels.

When a U.S. citizen returning from Mexico is flagged for having an arrest warrant, the man claims to have taken 20 morphine pills in order to avoid prison time; a shipment of car seat cushions coming into America is padded with more than foam.

A man entering the U.S. with more cash than the $10,000 limit raises eyebrows; officers find a cooler full of rat meat in the back of a traveler's vehicle, but further inspection uncovers something more surprising.

Travelers attempt to smuggle firearms within a load of sporting goods. Officers crack down on animal smugglers. Visitors like to bring home traditional gifts to their families in America, but there's still a limit to what can come across the border.

The border between the USA and Mexico is the busiest in the world. This series follows the work of America's Customs and Border Protection agency, whose job is to defend the border and stop terrorists, drugs and illegal weapons from entering the country.

Officers spot a lone pedestrian entering the U.S. with large bags; the search reveals containers of coffee, one concealing a package of suspected narcotics; the x-ray of a flatbed trailer reveals hidden bundles, but officers struggle to reach them.