A driver claims he buys used cars over the border to import into the U.S., but an X-ray reveals something suspicious in his spare tire; when a traveler returning from Mexico declares snacks at Customs, a Fish and Wildlife expert is called in.

An officer suspects a car is carrying more than innocent Santeria sprays.

Officers find an 18-wheeler carrying more than a load of takeout containers. A couple raises suspicion after declaring bulldog semen, but the labeling suggests the box may actually contain stallion semen -- a valuable and tightly regulated substace.

During his first day on the job, a rookie officer relies on his training, sending a hesitant driver for further inspection -- and his hunch pays off. When a traveler claims to be visiting his dentist bimonthly in Mexico, officers investigate further.

A traveler is caught with blades for cockfighting, a cartel-run blood sport. Every year, Mexico grows millions of dollars of flowers for the U.S., but cartels are taking advantage of the influx of shipments during major holidays.

Two men arrive in an SUV carrying enough suitcases for an entire family. Officers discover it's no family car -- it's a Kevlar-lined, bulletproof tank, the type that the cartels use to transport high-ranking gang mambers and attack law enforcement.

Cartels hope CBP won't inspect happy families, but officers know not to fall for that smuggling trick. Due to avian flu, live chickens can't be brought into the U.S.