Officer Hector Navarro stops a silver pickup truck at the Nogales port of entry. The driver is acting suspiciously and traveling alone, which is a red flag. A police canine is called in to sniff for narcotics, and a cleverly hidden trove of heroin is uncovered - breaking an all-time record for drug busts at this port of entry.

A report on illegal immigration follows drug smugglers and job seekers as they risk their lives attempting to cross the Mexico-U.S. border. Also: a look inside the U.S. Border Patrol. AKA Inside US Border Wars

Working the varied terrain of San Diego, California are officers and agents of the Department of Homeland Security; men and women dedicated to their duty of defending the United States busiest border crossing. Three components of U.S. Customs and Border Protection watch over this 66-mile stretch of the border and beyond from the air, on the ground, and at the ports of entry. Their mission is to secure the border against smuggling of contraband and unlawful entry into the U.S. In this episode of Border Wars, officers and agents in San Diego discover thirty people elaborately concealed in a tractor-trailer, race to prevent people from illegally crossing the border under the cover of a blinding fog, and unearth a payload of hundreds of pounds of marijuana carefully hidden behind the cab of a tractor-trailer.

On the U.S.-Mexico border, officers and agents work to fight the threat of terrorism while remaining vigilant against illegal immigration and contraband smuggling. In this episode of Border Wars, agents launch an uncover sting to stop an illegal human smuggling ring, chase down suspected illegal immigrants through the desert on foot, and discover a woman who hired smugglers to hide her in a car, saying her only goal is to be reunited with her son.

Meet the Shadow Wolves, an elite unit of just 12 Native American federal agents who hunt down drug smugglers crossing into the US through a desert the size of Connecticut using ancient techniques.

Examining the Sept. 30, 2010, death of American tourist David Hartley, who was allegedly shot by Mexican pirates during a sightseeing trip on Falcon Lake near the Texas-Mexico border.

In this episode of Border Wars, Border Patrol Agents and Customs and Border Protection Officers in Laredo, Texas, work around the clock to stop illicit drugs and undocumented immigrants from slipping into the United States through the countrys largest inland port. Horse Patrol and Air Support team up to track a group of immigrants hiking through private ranchland just north of the border; Agents at the Rio Grande face off with smugglers to stop a group of suspected immigrants from rafting across the river into the United States; Customs and Border Protection Officers at a Port of Entry bridge uncover a dangerous drug rarely seen here; and Immigration and Customs Enforcement Officers team up with a Laredo SWAT team to bust a suspected coke house.

A truck with canned jalapenos is found to have marijuana; a human smuggler will not give up stranded immigrants; agents raid a suspected stash house.

A stolen vehicle is abandoned after it flips over during a high-speed chase, and a huge load of marijuana is found inside

Agents beef up security in Miami in preparation for Super Bowl XLIV, while also patrolling the rest of the city for drug trafficking and illegal immigration.

Drugs, guns, cars and money are just some of the items confiscated on a typical day by Customs and Border Protection (CBP). But what happens to this contraband after it is seized?

CBP agents dismantle an observation point used by smugglers to monitor agents' movements in the remote desert, and seize a vehicle attempting to carry weapons and nearly $800,000 back to the Mexican cartels.

In this episode of Border Wars, agents and officers struggle to stop cartels and illegal immigrants whove found weak spots in spite of increased fortification along the U.S.-Mexico Border. Four feet beneath Nogales, agents crawl through a claustrophobic drug smuggling tunnel, knowing they could come face to face with armed criminals. Near the Port of Entry, Nogales Rail Inspection Team is on high alert as a freight train full of new automobiles rumbles toward them. Trains, with infinite hiding places, are becoming a favorite place for cartels to stash drugs: If the officers arent careful, they could easily miss a load. In the desert, Border Patrols only dirt bike unit races after a group of illegal immigrants. But in this sprawling Indian Reservation, the agents will need skill - and luck - to catch them.

With the help of a Blackhawk helicopter, agents arrest a suspected smuggler who is backpacking drugs into the U.S.

Customs and Border Protection patrol the crucial boundary between El Paso, one of the safest cities in the U.S. and Cuidad Juarez, considered one of the most dangerous cities in the world.

Border agents in Arizona defend a national park overrun by smugglers.

Border agents in El Paso, Texas battle to secure the city from human trafficking and drug smuggling.

Agents chase smugglers in a dangerous high-speed pursuit.

Agents patrol the Rio Grande Valley in southernmost tip of South Texas. They catch drug smugglers burying contraband in tanker trucks and illegal immigrants sneaking around highway checkpoints in the middle of the night.

Agents persue a pickup truck loaded down with drugs ferried from Mexico; a routine vehicle inspection uncovers a large stash of heroin.

A search team races to rescue a mother and her son who were abandoned by smugglers in the brush.

Agents put themselves in harm’s way searching for armed smugglers fleeing a shoot-out with the Mexican military. Once at the riverbanks, they find a suspected smuggler who has been shot five times. Their mission quickly changes as they rush to save the man’s life.

Drug smuggling has reached “Texas-sized” proportions in the Rio Grande Valley. A canine unit detects a suspicious vehicle coming in from Mexico, and agents discover a massive quantity of methamphetamine concealed within.

Law enforcement battles to intercept the massive flow of illicit traffic moving through the Rio Grande Valley. Agents in McAllen, Texas, track a group of illegal immigrants in the dark and find themselves outnumbered in a large field.

The Rio Grande River serves as a highway for illegal traffic and dangerous crossings. As the Department of Homeland Security’s surveillance intensifies, powerful drug cartels and human smugglers are trying more desperate tactics.