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

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Agents in South Texas work to stop drug dealers, smugglers and undocumented immigrants from infiltrating residential neighborhoods and getting innocent bystanders involved.

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?

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.

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.

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

A Blackhawk helicopter leads ground agents on an epic chase after an illegal immigrant through treacherous mountains near Douglas, Ariz. A live surveillance camera alerts Border Patrol agents to a known fence coyote who tries to guide illegal immigrants into downtown Nogales.

Agents and officers work around the clock to secure the border between El Paso, Texas, and Ciudad Juarez, Mexico.

South Texas has become a hotspot for smuggling activities on the border.

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 the Rio Grande Valley, money has become something of a drug — corrupting people's lives and luring them into believing in its broken promises. Officers at the Brownsville Port of Entry are performing a “blitz” enforcement operation — random searches for contraband — to deter the onslaught of smugglers. In nearby Laredo, Lucky and the narcotics unit hunt down desperate heroin dealers who are selling hits of black tar in school zones for $20.

Border Patrol agents cut off a getaway car as it tries to flee the scene of a drug drop in ranchland east of Nogales, Ariz. Agents arrest the driver and seize the drugs, then pursue the smugglers.

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.

Witness one of the Caribbean's largest drug busts of the year -- over 1.5 tons of cocaine worth more than $40 million found aboard a Panamanian fishing boat heading to the U.S. As the State Department negotiates for possession of the ship, the DEA and Coast Guard stand guard over the cargo. When a suspected smuggler requires medical attention, the situation becomes urgent in a scramble to get medication on board. Next, enter the underworld of North Miami Beach as officers patrol the streets.

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.

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.

When the Coast Guard rescues Cuban refugees from a remote island in the Mona Passage, Customs and Border Protection agents must race to intercept them and verify their identities.

Along the southern Arizona border at the port of entry, agents detain two families within a 24-hour period, driving similar SUVs and carrying a combined total of nearly $1 million in cash and drugs.

Downtown, Border Patrol and ICE agents discover a major drug-running tunnel and suspected smugglers may still be inside. With cartels watching their every move, they must risk their lives to map and destroy it.

In Puerto Rico, agents keep a high-value drug seizure from South America secure as they transport it back to San Juan. They also use a DASH 8 plane and radar to find and seize a small drug-running boat in the dangerous Mona Passage.

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

For those rare occasions when human skills are insufficient, Customs and Border Protection (CBP) agents and local law enforcement officers turn to their friends in the animal world for some on-the-job help. In Rio Grande City, Archie, a CBP K-9, helps agents track a group of illegal immigrants spotted passing through.

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

Tactical cat-and-mouse games used in the war on drugs.

The action never stops for Customs and Border Patrol (CBP) agents and local law enforcement who patrol the border 24 hours a day, seven days a week. As dawn breaks, agents track a group of suspected illegal immigrants from Mexico.

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.

A group of suspected drug smugglers is tracked by the all-terrain vehicle (ATV) night unit at Rio Grande City Station. No sooner are they apprehended than the agents must call in reinforcements from the CBP's air unit, Omaha, to track down a group of illegal immigrants hiding in the brush. Another team of agents searches for nine people missing in the Rio Grande, initially finding only one body. The search becomes more urgent when they find two more bodies the next day.

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.

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

At the border checkpoint in Hidalgo, Texas, a seemingly ordinary car is found to have firearms and ammunition hidden in its console and under its bumpers. Members of BORTAC, the tactical unit that identifies smuggling routes, discover what could be a remote transfer point for illicit goods. Further surveillance supports their theory, and the team hopes to close in on an active operation - if they can avoid detection by cartel scouts.

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.

Illegal traffic between the Rio Grande and the Falfurrias Checkpoint in South Texas.

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.