tonight on "nightline" -- exclusive access inside a massive three-day operation run by a special task force that calls itself "the pimp hunters." we ride along as they track their prey. and -- >> is this real life. >> -- for that famous cover. going viral means big business. and these experts say they know the secret formula. a cat named george and our intrepid reporter, can they create an internet sensation?

plus, katy perry unplugged. the teenaged dream singer and the reigning queen of pop, tells all about her family, the breakup with russell brand and her new smoothie. good evening. i'm cynthia mcfadden. tonight, an epidemic hiding in plain sight. an estimated 100,000 underage american girls in our nation's cities and suburbs victims of sex trafficking. over the weekend, abc news was granted exclusive access inside the biggest ever nationwide crackdown. in 72 hours, 79 kids were taken off the streets and over 100 suspected pimps were arrested.

abc's clayton sandell went inside the sting for the nationwide effort to tell the stories among those living among us. it's "hidden america." >> reporter: the sun has gone down but here on the streets of denver, things are just heating up. >> get your hands out the window. >> reporter: guns drawn, police swoop in on a man they suspect is a pimp on a nationwide sweep called operation cross country. fbi and local police spanning out in 57 cities. >> female wearing daisy dukes. >> reporter: a cat and mouse among those who traffic young men and women. >> who is a pimp? >> it could be white, black, hispanic, purple, green, it doesn't matter. >> reporter: sergeant john runs

a task force they call themselves the pimp hunters. forced into the sex trade, an estimates 100,000 children alone. >> people have a tendency to believe this is something from foreign countries and people being brought in from indonesia or something. which happens but it's also about our kids, our neighborhoods. >> reporter: the average age of a girl entering this life is 12. these girls rescued this weekend only 15. once on the street, many experts say many girls are approached by a pimp within 48 hours. >> the younger ones are so much easier to control because they're scared. >> reporter: the hunters are trying to offer that way out. detectives start by scouring online ads looking for what appear to be underage prostitutes. they pose up johns that set up a meeting. >> that's 250, right? >> reporter: others listen in from a nearby room.

the officers asked to us blur their faces for their protection. just before 6:00 p.m. surveillance teams outside this apartment spot the suspected pimp dropping off the girls. >> achiechevy maroon dropping oo females. >> reporter: inside the car, 21-year-old dwayne west. >> i'm just letting you know, your behavior is consistent with somebody who is pimping out. >> reporter: back in the apartment, two young women. west tells officers he has no idea what they're up to. >> you're not a pimp? >> no, not at all. >> reporter: the cops don't buy it, he's charged with a felony, but after making bail the next afternoon, he's free once again. >> i lived a privileged life. i went to the best schools. >> reporter: the purpose of all

of this is to save young women like austin when she was on 17 and on the streets. >> i thought he was going to help me get a job, not like he actually did. >> reporter: when your pimp made you go out on these calls, how did you get through it? >> i just blocked it out like it wasn't even happening. >> reporter: this denver team rescued her two years ago. >> what a terrible feeling that is to feel like 14, 15, 16, that your life is over. that no one's ever going to see you the way you want to be seen. >> reporter: she says she's now social, planning on college and is engaged. >> i never would have seen myself getting out of it this situation and on top of that going on and being successful the way i am. >> reporter: but the problem isn't going away. dan steele is back on the

street. and within an hour, the man arrested the night before dwayne west is arrested again. >> twice in 24 hours, huh? >> reporter: a sign that the pimp hunter's work is never done. for "nightline," i'm clayton sandell. >> making the invisible visible. up next, a cat-loving reporter and his flying fe inin on a quest for viral video fame. ♪ loyalty discounts, safe driver discounts, paperless discounts. progressive keeps finding me new ways to save me money on my car insurance. you're sure to save it forward. i see you're a healthy eater. you qualify for a healthy eater's discount. oh, my gosh! thank you. you're welcome. dropping off the shopping cart discount. why are you doing it? because of the hundreds i saved at progressive. and that's when i told her about progressive online!

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well, the kids who shot internet fame because of something funny, well viral videos can make instant celebrities. how you can make one video stand out among that sea of babies and flash mobs. abc's dan harris brought in the experts. >> reporter: going viral from david and the dentist. to the old spice guy. in virality is perhaps the biggest enter aat the same time. paying millions to make it happen. some will makes it actually work with an age of information overload with sfool hours of video uploaded to youtube every minute. how does one video cut through. i got a rare look inside when i was approached by these guys from an advertising agency

called mekanism who have created viral sensations like pepsi's ad with the rapper enthem in. >> damn, that is pretty good! >> reporter: a few months ago, they came to me with a big promise -- >> make dan harris go viral. this is essentially what we're going to do. >> reporter: at the "nightline" offices we had a reverse of strategy sessions which they picked videos mostly that would have ended my journalism career. >> dan harris cat freak. one where i was portrayed as a cat horder. and then one where they wanted to edit my ego into serious interviews with people like the dalai lama. >> an air horn? >> reporter: finally, we thought it would be safer to just make a video for one of my favorite charities, the aspca. >> i like the sound of that. >> reporter: which works to save the millions of dogs and cats

who are put down every year because they can't find a home. so one day in february, we went to a studio in new york -- >> and action, dan. >> reporter: -- to shoot a video called "hovercat" with the expert george. george and i thought our theme. >> we're going to do a couple more of these then we're done. okay, here we go. >> reporter: then they had george jump up and down in front of a bank of cameras to make it look like he was flying. this is the same way they had the flight cruise from matrix. a few weeks ago, they e-mailed me the hover cat video. in it, you see me in what is supposed to be my my apartment, taking the final sip of coffee before leaving. that is when george flies off,

levitating, taking a quick snack, bouncing on the bed before falling in my arms when i come back home. finally, the kicker, really a tag line, millions of viral videos waiting to be adopted. i love it. i love it. but now they had to make it go viral. >> this is our framework for engineering virality, making things go viral. >> reporter: their strategy keys on something calls influences, people with big audiences who may be receptive to cats. they provide a whole spreadsheet of influences. >> they want to reach out so i could have cheeseburger. >> reporter: on june 10th, the plan goes into action. it debuts on "good morning america." we're going to start with the video that we're hoping will go viral. veronica belmont, a technology reporter and cat lover tweeted it out to 1.6 million followers.

after that, mystery guitar. and then a massively popular site called "i can't have cheeseburger" posted the video. that got hover cat to 2 million views. >> it drops because we sort of pulled all the biggest influences already. >> reporter: that's when they started pushing it to nonanimal sites like the information tech blog mashable. from there, mainstream, "usa today," l.a. times, huffington post. even the british newspaper, the sun, boom, that was it. by day four, hovercat had 500,000 hits. the mekanism guys showed me the graph of online virality. >> somewhere in here there's the virality? >> yes. >> reporter: as we go on the

air, hovercat has over 800,000 views. were you nervous it wouldn't take on? >> yeah. >> reporter: thanks for giving it a shot. >> my pleasure. >> reporter: the end result -- the internet has the newest celebrity cat who is both an object lesson in engineering virality, and a furry face that could possibly help save millions of animals who need homes and their own shot at going viral. for "nightline," this is dan harris in new york. >> oh, dan, let's see if we can do, get dan's hovercat to 1 million hits. go to abcnews.com@nightline. just ahead, she's the pop princess with mega hits like the one that got away. katy perry opens up next. ♪

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♪ ♪ if i was your boyfriend i'd never let you go ♪ she's known for her outrageous costumes, techni color hair and chart-popping hits. but now, another side of katy perry. in a new concert documentary she's pulling back the curtain on her private life. here's "20/20" co-anchor elizabeth vargas. >> reporter: in just a few short year, katy perry has become a

reigning queen of pop selling over 75 million singles. her last album generated five number one billboard singles making her the first female artist to such such a record. the only other artist to do that is the self-titled king of paper michael jackson. ♪ i'm a man a man come on >> reporter: the youtube video earned more than 1 billion views. a figure that transformed into box office gold when she releases her new movie next week. a film called "part of me" which combines never before scene behind the scenes footage of perry with dazzling performances. >> i just put out "teenage dream" and people were responding to the video. and i went and booked my tour with management, and everybody wanted to come. and i thought to myself, well, i think this is going to be a

moment, maybe i should catch it on tape. >> reporter: showcasing that trademark perry sun, we get to see the origin of the crazy costumes. >> she's got so many looks that she can pull off which is so fun for us. >> reporter: we also get to see the origin of katy cost tellic, building back to her blond roots, her strict evangelical upbringing. >> a lot of people had read about the dynamics between my parents and myself and how they're the traveling ministers and i'm kind of the black sheep. >> reporter: if you follow the hair, she's also the green sheep. the blue sheep. what is with the hair? >> i just like having fun. my parents have become more receptive and tolerant as i've globe up into an adult. >> reporter: over 300 hours of footage, the movie captures all the ups and downs that come with life on the road. so was there any sort of

hesitation about putting yourself out there? on this movie? >> not exactly with this. >> reporter: of course, if there was any hesitation on perry's part it would have to be discussing her failed marriage and divorce to comedian russell brand, the story line that's been playing itself out in the tabloids and over the airwaves the past few months. at this year's grammys, perry sang a song called "part of me" with lyrics that seemed aimed at one particular person. ♪ you chewed me up and spit me out ♪ >> reporter: in the movie, the effects of the relationship are laid there. >> being in love and the reality of making it work with the marriage is not like the movies. there's a lot more compromise, a lot more sacrifice. or it's not going to work.

i thought it would have been strange if i had completely avoided it but i wanted to be very delicate and respectful about it, and hopefully, you know, people see that problem, they see me having that problem. they're like, oh, well, even she can't dodge life's curveballs. it's like a scar, sometimes, you look on your arms or legs and you see this scar. and it reminds you of the thing that you learned or whatnot to do again. ♪ >> reporter: and if there's one recurring lesson about her lyrics, it is that no matter who you are or how you look, there's going to be something out there for you. do you still believe in love? >> do i still believe in love? >> reporter: yeah. >> of course. i'm going to let love lead the way and i think i'll stick to it. >> reporter: for "nightline," i'm elizabeth vargas in los angeles. >> perry's "part of