When an older couple crossing into the US has cartel logos on their packed clothes, they have some explaining to do. A Mexican driver says he's visiting a friend in Texas, but seems nervous. A vehicle search finds evidence of hidden compartments.

When a man is detained on a warrant, the mug shot confirms they have the correct man -- but his fingerprints aren't a match. A woman arrives at the border driving an oil worker's truck. Upon inspection, officers find white powder around the opening.

A woman claims she drove 13 hours for a 15-minute dentist appointment, but she can't remember the name of the dentist, and has no proof of her visit. Two men returning from a night in Mexico are pulled over after officers detect a strong smell of weed.

A man tries crossing with cosmetic injections stuffed into a sweet treat. A rookie officer follows a hunch after a Canadian narcotics smuggling trend.

When an American band is denied entry into Canada due to incorrect paperwork, CBP officers have to investigate. A U.S. citizen coming back from Mexico is flagged as having an arrest warrant -- while officers dig deeper, she attempts to escape.

A man traveling with his young daughter attempts a U-turn before the border and comes face-to-face with CBP officers. A stand-up comedian is stopped after declaring prescription meds, but further analysis shows that the pills test positive for fentanyl.

During the holidays, hundreds of thousands of people cross in and out of the US to spend time with their families, bringing with them gifts -- some naughty, some nice. But it's business as usual for the cartels; they blend in with the holiday traffic, making the season of goodwill no vacation for the officers of Customs and Border Protection.

As another year draws to a close, our thoughts turn to new beginnings and fresh starts. But at the border, some things never change -- certain old acquaintances aren't easily forgotten, and not all resolutions are destined to last. Here at America's front line, the one thing that's guaranteed this New Year is that the battle against smugglers never ends.