Tonight, we begin with a look at airport security and what's on the other side of those security lines. Big, crowded airports like miami international, the pressure of delivering 100,000 stressed out... See More
Tonight, we begin with a look at airport security and what's on the other side of those security lines. Big, crowded airports like miami international, the pressure of delivering 100,000 stressed out passengers safely to their destination every day makes for no shortage of human drama, as my co-anchor bill weir discovered. Reporter: Let's say you're on a flight into miami. And the guy next to you comes completely unhinged. Sir, I need you to take a seat right now. I paid a lot of money for this seat. Reporter: While you watch flight attendants struggle for control, what you'll never see, what you ever see is an airport the size of a small city spring from defense to offense in a blink. Bolds move as word spreads. All right, guys, go ahead. It's on you. Reporter: From pilot to tower, where intense eyes flick past the 1,500 camera feeds to find that corner of the runway known as the penalty box. There, while engines wind, guns approach, held by miami-dade cops. Rear guard, go around. Reporter: And since this is an international flight, customs and border patrol. Put your hands up! Put your hands on top of your head. Reporter: All of us on the plane knew this was practice, but still. Heards pound in moments like this, embarrassing mistakes can be made. And the fact that mia officials invited "nightline" to watch further proves they are pulling back the curtain down here in unprecedented ways. Airport 24/7 is the first reality show given access to the sort of high and low drama that plays out here every day. As 100,000 personalities collide. Cameras are romming when item persons flare. When drugs are found welded into auto parts and when arguments erupt over carry-on peanut butter. The size is too large. You can bring a little one, 3.4 ounces or less. But this is too big. . Reporter: They're romming when dogs sniff out a suspiciously large stack of cash, when a gun is found in a carry-on bag and a knife is discovered in one man's shoe. All part of the routine in a place that has a small museum of would be carry-on weaponry. What was in that person's mind when they walked through our checkpoint? Reporter: Lauren is not only the director of security at mia, she is the head of pr. And while many in her position may disagree, she sees this publicity as a security tool. We believe this is going to show the public what we do for their safety. We're not giving away family secr secrets. Reporter: No? The only thing we want the bad guys to know, we're serious about security so take it somewhere else. Reporter: What they mostly reveal is a relentless game of cat and mouse. And dog. Hey. How are you? Reporter: On this day, tyson is set out to sniff a cargo plane from costa rica, full of fish and cilantro. Customs agents know how smuggle earls mark boxes with innocent-looking numbers and how a dock worker who sneaks something past the gates can make 5,000 bucks. They seize close to 21,000 pounds of drugs last year, but on this day, come up empty. So, there's a chance that tyson might have smelled, might have made a mistake? It's a possibility. Some days are good, some days are bad. Reporter: In the international terminal, tyson's stubbier colleagues are trying to head he kind of plants that could carry devastating crop disease into the u.S. But they've also found a full assortment of oddities over the years, including body parts and fetuses used in haitian religious rich warms. Birds -- Reporter: Live birds? Yeah. Smuggled in birds, yeah. Reporter: But bird smugglers are small potatoes in a category x airport like this. The designation given on to the most prime targets of terror. The average traveler still resents taking off their shoes. Right. Reporter: Still thinks that this is sort of, security theater to make us all feel better, but -- maybe al qaeda is not going to do it the way they did it before. We know for a fact that we are still the prime target for terrorism here in the united states. And we know there are threats here. There's insider threat. Reporter: Customs and border protection, they're, on a weekly, monthly basis, catching terror suspects that we never know about? They may not put out the press release, but I'm going to tell you that it is a fact, that these things do happen. Stand up, sir. Reporter: Back on the jet, the angry actor is lead away. Pretend pengers deplane past drawn weapons. And the officers in charge cool off and reflect. Are you wore ripped you are giving something away by showing us this? We still got a lot of secrets in our bag. You know, this is nothing compared to what we can bring on to an organized group of bad guys, whether domestic, international terrorism, whatever, that want to come and wreak havoc. We got something for them. Put your hands up! Reporter: Here's hoping they never have to prove it. I'm bill weir for "nightline" in miami.
This transcript has been automatically generated and may not be 100% accurate.