this is "nightline." tonight. >> she made the escape. how brave is that? >> new details about the horrors endure the by 13 year old enclos closs. >> now john walsh's son is joining him in a brand-new show "in pursuit." >> the most important thing is a photo of that child. >> taking capturing criminals to a whole new level. plus, going too far for fame? the latest high-profile anparticular thantick that could have turned deadly.

can anything be done to slow down the risk taking? >> your parents would say, if your bridge, would you do it too? and one of the largest great whites of the world. but first, the "nightline" five.

we begin with a man whose personal tragedy turned him into a household name. tonight john walsh of america's most wanted is upping his game, with a new show that taps into the power of social media, as the latest high-profile case continues to unfold. here's byron pitts. >> you can tell that she's not quite the same. >> we have two parents of a 13 year old who are deceased. we have a 13 year old who was abducted for 88 days against her will forcibly. it doesn't get any more serious than that. >> reporter: for 13 year old jay jayme closs, the hearing her father shot and

watching her mother die. >> you did cause the death of denise j. closs. >> reporter: closs escaped and ran for h woman approach me. she was crying and said i need help, i don't know where i am. i'm lost. please help me. >> reporter: thin, disheveled but alive. an outcome all too rare. perhaps no one understands it better than john walsh. >> we were holding out hope she was alive. she not only saved herself, she also caught her own perp. in the time she was in there, she found out his last name, what his car looked like. a description, a mazing for a 13 year old. >> reporter: his 6-year-old son was abducted. >> there were no amber alert, no media coverage. i had to beg to get on good

mour morning america. >> reporter: they made shuure t abduction became national news. but adam had been murdered. >> i don't know who would do this to a 6-year-old child. and i said we've got to find your wife and we've got to tell her. and i said you know what? i'll tell her. i'll be the one to tell her. toughest thing i've ever done. >> reporter: the case would remain cold for decades. walsh turned his attention to making sure no families had to . >> this is america's most wanted. >> reporter: perhaps best known for his work on the show america's most wanted. >> the next time i see allen's face, i wauchts nt to see bars. >> reporter: agencies around the world and the country depended on it.

>> they said john, you have 1422 of the world's most dangerous fugitives, more than any fbi agent in the history of the country, and you're private citizen. >> reporter: over 20 years later his own son's case still unsolved. he called this man to help solve the mystery. in 2008, based on these two pictures and a mountain of evidence, the detectives pieced it together from a different way than the original detectives. the new hollywood police chief officially closed the case by naming the man who killed him. >> he would be arrested for the abduction and murder of adam walsh on july 27, 1981. >> it took 27 years to soflve that case. most people don't get that help. >> reporter: how often do you think about it? >> every day. i'll always be the parent of a

murdered child. and it's a wound that cracks over on holidays and birthdays, but i don't bleed to death. i never gave up. and i wanted do honor his memory, and he's my angel. >> reporter: after adam's death, walsh and his wife became advocates and would help found the national center for missing and exploited children. there are more than 4 20,000 reports of missing children by law enforcement last year. >> i believe children are and can be resilient. they have something we don't have. they have this ability to look at the good side of the public. >> repthere's still so much dant there. >> i'm john walsh and this is in pursuit. >> reporter: he now has a new show, in pursuit with john walsh on discovery, where he can bring attention to missing children in

each episode. this time he's joined by his son callahan. your father took us to places. he was our eyes and ears on the ground&t around the world, now that's going to be you. >> i spent my time following my dad and being in a family who lost a child, i have empathy for these families. >> reporter: in one episode, the story of a 30-year-old manhunt. >> if he's still alive, he's a horrible creep dirt bag who murdered a very nice young man. he's been out there 30 years. he needs to be brought back to justice. >> reporter: what perspective do you think with your youth being a different generation, what will you bring to the show that might be different. >> this show is, we're harnessing the power of social media, the most important tool is a photo of that child, social media is going to harness the

power of the public like the hotline did, and we're going to use it as a tool for our viewers to engage them and give us the tips that we need. >> reporter: walsh knows all too well how important raising awareness can be. he's helped publicize several high-profile cases like elizabeth smart. >> the smart family asked me to fly there the day she was recovered. and when i saw elizabeth walk down the stairs that night, i said this is good. >> reporter: and jaycee dugard's. >> it's been exactly six months since the blond sixth grader was kidnapped. >> reporter: with closs's case being the late east to hit headlines, he talks about bus surfers. >> they'll figure out if that kid goes home alone, if they have to walk half a mile or

quarter of a mile. they figure out how they're going to get that kid. it's like hunting. >> reporter: what you just said will horrify a number of parents. because most kids go to school, come home, there's no drama at all. >> i've been telling parents for years, that the national center has done research the last ten years. the most vulnerable time for a stranger abduction is on the way to school, from the bus stop to school and at night. the bus surfers look for the individual kids that grab their fascination and that they can get the easiest from that bus stop. >> reporter: by his own account, john walsh has spent a lifetime digging, searching the underbelly of society. seeking not revenge but justice. >> the problem and the challenge is to keep those kids' pictures and their memory alive. we never give up. i've learned over the years, don't give up. anything you can do. >> reporter: we in america love

happy endings. will jayme have a happy ending? >> she's alive. she made it. she made it out. she's not just another picture that we're not going to figure out what happened to her. i hope i get to meet her some day. i'm going to tell her i'm really proud of you. >> reporter: i'm byron pitts in new york. >> our thanks to byron. in pursuit airs wednesdays on 10:00/9:00 central. up next, the latest social media challenges. a challenges. and you have the determination to keep going. humira has a proven track record of being prescribed for over 10 years. humira works inside the body to target and help block a specific source of inflammation that contributes to symptoms. most adults taking humira were clear or almost clear and many saw 75% and even 90% clearance in just 4 months. and the kind of clearance that can last. humira can lower your ability to fight infections, including tuberculosis.

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it's as if each new day brings a new social media challenge. many are harmless fun, gets you clicks online. for many, the lure of internet fame has them taking increasingly dangerous risks. >> reporter: this falls into the category of we shouldn't have to tell you not to do this. >> [ bleep ]. >> reporter: 27-year-old vancouver, washington resident, nick, jumped off the 11th deck of royal caribbean's 238-foot tall symphony of the seas ship while it was docked in the bahamas after a night of drinking with friends. >> it was my idea. everybody turned me on and i just did it. >> reporter: the video, which was posted to instagram last week has since gone viral, wracking up over 200,000 views.

>> it's like the old saying where were your parents would say if your friends jumped off the bridge, would you do it too? well, they are. >> reporter: he was picked up by a small boat nearby. royal caribbean calls it stupid and reckless behavior. the cruise line has also banned him and his friends from ever sailing with them again and kicked the group off the ship. >> after i jumped, calculated how high i jumped, then i realized how serious this was. >> reporter: medical experts say falls from seven storeys or higher have a 90% chance of ending in death. he luckily survived his jump from 11 decks up. >> about six or seven hours after, i was in quite a bit of pain, and it took about three days for that pain to go away. >> reporter: his stunt is just the latest example of the extreme lengths people are going

to garner attention online. one of the latest crazes to hit the internet is the bird box challenge, inspire the by the new netflix horror movie "bird box." >> under no circumstance are you allowed to take off your blindfold. >> reporter: it sparked this dangerous challenge where people were blindfolding themselves, attempting to do every day tasks. one utah teen even attempted to drive with her eyes covered. she swerved into another lane and crashed into a car. netflix posted about doing activities while blindfolded, writing, can't believe i have to say this, but please do not hurt yourself with this bird box challenge. and youtube has been trying to crackdown on videos that promote harmful or dangerous activities. just this week they updated their policy that says

challenges that present a risk of death are not allow on youtube. this past summer, it was the kiki challenge, which featured people jumping out of moving cars to dance in the middle of the street. perhaps unsurprisingly, it didn't always work out. >> hey, kiki, do you love me. >> reporter: that social media craze took over the internet in part thanks to this guy, shigy, the internet comedian posting this of him dancing to "in my feelings." he #do the shiggy. and it took off. it morphed into what we now call the kiki challenge which comes from the lyrics in drake's song. more than half a million hash tags have been used on twitter of people participating.

but things got dangerous when people started jumping out of moving vehicles. some of these videos were down right shocking, like this guy, jalen norwood. don't worry, he's okay. norwood appeared on jimmy kimmel afterwards. >> how you doing, jaylin? >> pretty good, livin' life. the plan was he was supposed to come slow. and i was going to jump on the hood and continue dancing. >> are people recognizing you now? >> oh, i'm the most famous guy in florida. >> you want to walk on your own? >> reporter: but this woman was not so lucky. >> last thing i her wremember w opening my car door. >> reporter: this 18-year-old was treated for a skull fracture, blood clots and bleeding in her brain. >> it may seem fun and may seem easy, but at the same time, they could be so dangerous. >> i think people are risking life and limb for these social

media challenges, because sadly, that's really what is driving our youth. they want to be famous. >> reporter: the history of online subjec online stunts goes back years like in the early 2000s with the cinnamon challenge, or the kylie jenner lips challenge. but these amateur attempts are nothing compared to professional thrill seekers whose livelihood often depends on how many clicks they get. and the more daring the stunt the more eyeballs on their posts. >> when you put money into the equation, fain inme into the eqn people are almost willing to do anything to gethose things. >> reporter: it's part of new internet adventurers, producing slick videos that they say celebrate life. high on life has more than a million followers on instagram and more than 600,000 on

youtube. >> their job is to go around and travel and have a good time. isn't that what we all want? >> reporter: the group's members post videos, frequently highlighting hazardous activity, for example this daring balcony dive. one member posted this video, a dare devil walk down a 300-foot-high abandoned train trestle. shortly after that, another expedition took a terrible turn. another high on life member, died after they plunged 100 feet from one of canada's tallest water falls. and that could have been this man's fate. he now hopes his story will caution others against making the same mistake. >> i realize how dangerous this is. the height is pretty high. and at that height the water is, i mean, it's almost like cement. i would never do this again.

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and finally tonight, she's a massive great white, a living legend of the seven seas. new video out of hawaii is turning heads around the world. her name? deep blue. perhaps the biggest shark on the planet, believed to be 21 feet long, grabbing a quick bite off the island of oahu. the diver reaching out her hand, escort the by two dancing dolphins, believed to be 50 years old, deep world. the organization behind this video, one ocean, is hoping it will raise arene a

plightfseiasf e deep and the need for more laws protecting them. and if you want to check out our full episodes, check us out on hulu. good night, america, have a good weekend. weekend.