this is "nightline." >> kiefer sutherland is taking you behind the scenes of abc's "designated survivor." >> sir, you are now the president of the united states. >> inside the secret preparations for possible high-stakes catastrophic events. and meet a real-life designated survivor. . plus, smoking hot. ? so baby pull me closer ? >> the biggest pop stars of the moment. chart-topping songs and addictive tracks. but who are they? we're getting closer with the chain smokers. but first the "nightline 5." >> my hygienist said the most random thing, think of my teeth like an apple. could be great on the outside, not so great on the inside. her viad, use a toothpaste and mouthwash that strengthens both.

uniquely formulated with active strength technology to strengthen teeth inside and is better at strengthening the outside than colgate total. >> makes my whole mouth feel amazing. >> advance to healthier gums and stronger teeth from day one. >> my checkup was great. >> crest. healthy beautiful smiles for

good evening. thank you for joining us. it may have been spun into a hollywood tale but the idea of a designated survivor is in fact very real. each year there's one secret person who's ready to assume the top job in the event our government is wiped out. what's it like to be a real-life designated survivor? here's my "nightline" coanchor juju chang. >> there's some kind of explosion in or around the

unthinkable. the doomsday scenario. a catastrophic attack on u.s. soil. the president, congress, the upper levels of government, all wiped out. while it's the stuff of dark thrillers, the creators of abc's most talked about show "designated survivor" have something very real in mind. >> sir, you are now the president of the united states. >> so this is your presidential motorcade? >> i'm seeing it for the first time. this is a small one. >> reporter: the series marks a return to television for kiefer sutherland, playing a meek, low-level cabinet secretary. >> i, thomas adam kirkman, do solemnly swear -- >> reporter: who's thrust fully unprepared into the role of president. it's based on a very real, extremely classified safeguard, known as the continuity of government plan. >> the problem that the continuity of government plan

>> reporter: abc news consultant and former counterterrorism official dick clark ran the program. he's the only official to ever deploy it in a crisis. during 9/11. while president bush was in the air, vice president cheney was rushed to an underground bunker. >> on 9/11, i activated the system. the continuity of government system. and we asked the speaker of the house to leave washington. we landed a helicopter on the grounds of the capitol, got the flew him out of washington. because we didn't know at that point whether or not the white house or the capitol were going to be hit by hijacked airplanes. >> reporter: it's like something out of a spy novel. using secret nuclear-proof bunkers like this now-declassified one under the posh greenbriar hotel in the mountains of west virginia. the concept, a remnant of the cold war. but each year a cabinet member is still asked to skip the state

>> they are put in a secure location with a support staff before the state of the union begins, and they're brought back only the neck monxt morning. >> reporter: former u.s. attorney general alberto gonzalez once served as designated survivor during president bush's 2007 address to joint houses of congress. >> madam speaker, vice president cheney, members of congress, distinguished guests -- >> my fbi detail drove me to andrews air force base. there were a group of individuals there from various departments and agencies all carrying these black binders. their job was to advise me in the event that i assumed the presidency. then i settled in in front of a large monitor and watched president bush give his state of the union. >> we must have the will to face difficult challenges -- >> reporter: he talks about his experience in his new book "true faith and allegiance." >> it suddenly hit me in the middle of that speech, oh my

i thought, oh my gosh. i've experienced pretty big moments before with president bush. i've advised him through two wars. i was on the oval office porch on the evening of september 11th when president bush came home that historic day. it really kind of hit me sitting on that airplane. i looked around the plane. at those that were with me. i wondered, would we be up to governing a wounded nation? >> where's the president? >> in the bunker. >> reporter: the white house going down is often a hollywood plot line. terror cells in "olympus fallen" -- >> olympus is fallen! they're taking the white house! >> reporter: two-timing double agents on air force one -- >> get off my plane! >> reporter: or tentacle-covered alien invaders on "independence day." >> welcome to earth! >> reporter: this time a marquee terror attack. the show invited us to this

training base. this will be the area where you actually film the scene? >> he and i will be here. they'll be actually training rough the compound. >> action! >> reporter: the action scenes are high-octane. but pondering how an average joe migh r suddenly becoming commander in chief -- >> where are we going? >> presidential emergency operations center. >> reporter: is what makes "designated survivor" a thinking man's thriller. this character has to spend a lot of the time thinking about what it means to be a good president. what it means to be a good leader. what d a good president? >> i think maybe you have to try and not be a good president. you have to try and be a good person. >> you're also one of the eps on the series. do you ever get temptedo bring the current presidential climate into this storyline? >> i think it's impossible not to. certainly in the context of our show, we have an opportunity to overcome the divide that seems to have taken hold in america. >> give me a kiss. >> mwah.

>> it's nice to see him play a loving, sweet family man. is that a side of you the audiences are going to be able to connect to? >> i think over the course of "24," we made 216 episodes, i think the only time he smiled when is he shot nina meyers. so i smile a lot more in this show. >> reporter: sutherland is referring to counterterrorism agent jack bauer. his bad-ass nearly a decade on "24." your character is not a hard-core political operative. he's also not jack bauer. >> not by a long shot. i'm looking behind me. all of these weapons. my character wouldn't know how to hold that, let alone fire it. jack bauer was very practice efficient in that. the one thing they do have in common this is commitment to serve publicly. >> this is the nuclear football.

the nuclear football. you say, what's the code? >> do i have an eye scan? >> do you need my fingerprints >> no, sir. or something? it's not like the movies. >> the guy laughs and says, yeah, we don't do that. >> reporter: the show going to great lengths to keep things realistic. >> we're here on the toronto set of "designated survivor." the cast and crew hard at work. all of this is the stand-in for a swanky neighborhood i alexandra, virginia. every detail well thought out. all the way down to the wash the president's speechwriter, veteran actor with real-life white house cred. >> mr. president, maybe the country's not ready yet. >> reporter: kal penn, everyone's favorite stoner from "harold and kumar." even played a terrorist on "24." then famously left hollywood to serve in the office of public engagement in the obama administration. >> compare and contrast the working conditions inside the beltway versus inside hollywood.

>> come on. >> it's so far-fetched. look, i have an air conditioned trailer and somebody will bring me a coffee if i want it, here. there -- >> you're in cramped quarters. >> i'm eating vending machine sandwiches and working 19 hours a i love that. but this is definitely the make-believe version. >> reporter: on set penn became a fact checker. >> the kal penn seal of approval? >> flattering. it's little things. how many people would be in a particular office? would somebody actually run into this person or creative license with it? >> reporter: they brought in a hard-hitting political consultant from washington, d.c. >> you are a speechwriter. >> i was for two senators and four cabinet secretaries. worked on a couple of state of the union addresses. >> sorry, sir, i told him you were busy. >> that's all right. how can i help you? >> how realistic is the oval office you built? >> remarkable. in the white house men's room there's an old-style mechanical shoe buffer with red and black

detail. >> that's weird. >> reporter: while they might not get everything right -- no doubt all the drama will feel true to life. >> our thanks to juju for that report. you can catch "designate d survivor" here on abc wednesday at 10:00 p.m. don't go away and don't let me down. up next, the electronic dance duo that has their minds. i struggle with bipolar depression, and it's hard.

i miss out on life's little moments. so i talked to my doctor and he prescribed latuda. there are many forms of depression. latuda is fda approved to treat bipolar depression, which is different from other types of depression. in clinical studies, once-a-day latuda was proven effective for many people struggling with bipolar depression. latuda is not for everyone. call your doctor about unusual mood changes, behaviors, or suicidal thoughts. and young adults. elderly dementia patients on latuda have an increased risk of death or stroke. call your doctor about fever, stiff muscles and confusion, as these may be signs of a life-threatening reaction, or if you have uncontrollable muscle movements, as these may be permanent. high blood sugar has been seen with latuda and medicines like it, and in extreme cases can lead to coma or death. other risks include decreased white blood cells, which can be fatal, dizziness on standing, seizures,

avoid grapefruit and grapefruit juice. use caution beforg or opera. amy is part of little moments with the family. ? and those everyday moments feel special to us. ask your doctor if once-daily latuda is right for you. pay as little as a $15 copay. visit latuda.com it's endless shrimp at red lobster. with another new flavor you never saw coming... grilled, glazed korean bbq shrimp. new parmesan peppercorn shrimp. just come in before it ends. introducing the new turbocharged golf alltrack. [ clearing throat ] the new golf alltrack. [ upbeat music ] with 4motion all-wheel drive.

the chainsmokers are arguably the biggest stars in music. many people still have no idea who they are. casual fans might even assume since most of the male duos' hits feature female voelks. nick watt thankfully is here to clear up all that confusion. ? so baby pull me closer ? note in the back seat of your rover ? >> reporter: this song's been number one for six weeks now. ? don't let me down ? ? don't let me downtown down ? >> reporter: this one also top ten right now. summer anthem. ? don't let me down don't let me

the biggest pop stars in america, traveling the world, living the life. note there's nobody ? >> reporter: the chainsmokers. you may know them from their slightly irritating novelty 2014 breakout hit. >> first let me take a selfie. ? >> reporter: then from a splashy billboard magazine article you get the impression they're dreadful bros bragging about drinking, talking about the size of their manhoods. if these guys are the f music are we in trouble? meet the chainsmokers. you guys came across like real -- >> yeah. >> i won't use the word. >> yeah, yeah. >> did they get you wrong? or are you? >> there are parts of that we don't like, parts we do like. i think we should have done a better job conveying how hard we work on our music. >> we do 250 shows a year. yesterday we had a show, tomorrow we're back in vegas, we've got miami, austin, vegas

little. >> the [ bleep ]. >> reporter: they're not braggadocios bros. >> "don't let me down" was on the radio. we're unassuming dudes. and the guy was like, "god, i'm so sick of this song." and changed it. and i was like, i don't even want to tell him. >> reporter: neither drives a car. both have uber ratings of over 4.6. i like them. let's move their ouvre is electronic dance music. >> sitting here making unique sounds, spent an hour the other day with a mike. >> reporter: what's with the name? >> at the time of conception it was totally just like, in college, you know, enjoyed smoking weed, you know, such a -- yeah, the domain's open, i don't have to have any underscores. >> it's just aname. yeah. >> the domain name was open. >> reporter: they collaborate a lot. drew also sings.

it's an old man question. >> we play all the instruments on our records. just like any band would. >> reporter: and then they futz with it on their laptops. >> i'll play a bass guitar to get that vibe, the sound of an actual real bass. but then i'll cut out the low end which is what a bass is really for and add a sub under it so i get the super-low synthetic feeling. and i get the -- but it's indistinguishable, just sounds like i'm playing bass. >> i have no idea what you're great. about but it sounds >> reporter: the problem with having everything on a laptop, they can crash. they've lost a trove of songs. ? don't let me down ? >> "don't let me down" was one of the songs we lost. i had to remake the entire song from scratch. having to like go back through that creative process was crazy. >> reporter: girlfriends? >> they've been with us before -- >> before fame? >> before all this craziness

friends. >> okay, i'm impressed that you're with the same girlfriends. >> they're really cool. if you met them -- >> it's really hard to meet people that are compatible and are willing to be supportive, you know, of our lifestyle. ? ? i need ya ? >> everyone's fortunate enough to be doing what they love. i mean, we're really lucky. i was a receptionist before this. at an art gallery. know what i mean? ? now it's in my head ? >> music was clely heart was. >> reporter: they're big social media guys, posting videos left and right. super sharers. >> i don't think there's a lot about our lives that we don't let people see. >> we've always just been kind of two dorky dudes that are pretty self-deprecating. >> do you get stopped on the street? >> sure. >> people think you're roger federer? >> yeah, all the time. >> i wonder why they keep handing me tennis rackets. >> reporter: there is a downside. >> you wake up in the morning, check twitter, the first comment

you'd die." >> i can't believe this is what i wake up to now. >> someone tells me the other day, nick watt looks like pee wee herman's pedophile uncle. >> you've got to appreciate that. >> reporter: back to the song. 463 million youtube hits. and counting. what put you on the map was perhaps my least-favorite song of yours. >> we were like, this is funny. it's a joke that we were going to make for our friends in new york city. then the world is like, this is who you are. we're like, >> right, right. >> that's our sense of humor, but like, we're going to try and show you some other sides of what we do now. ? ? >> i don't know if you made a conscious decision, i'm done, i'm going to make what i want to make, what feels cool, i don't care if you can dance to it, i don't care -- i mean, i care, but i want to make music that i like. that was "roses."

? take me back to a time ? >> reporter: "roses" and the rest madehem the biggest pop stars in america by being themselves, making music they like. long live the chainsmokers. i'm nick watt for "nightline" in west hollywood, california. and next, a celebration as the last remaining victim of the pulse nightclub shooting is released from the hospital.

i'm claudine and i quit smoking with chantix. smoking's a monkey on my back. it was, it was always controlling your time, your actions, your money. it had me. it had me. i would not be a non-smoker today if it sn't for chantix. along with support, chantix (varenicline) is proven to help people quit smoking. chantix reduced my urge to smoke some people had changes in behavior, thinking or mood, hostility, agitation, depressed mood or actions while taking or after stopping chantix. some had seizures while taking chantix. if you have any of these, stop chantix and call your doctor right away. tell your doctor about any history of mental health problems, which could get worse or of seizures. don't take chantix if you've had a serious allergic or skin reaction to it. if you have these, stop chantix and call your doctor right away as some can be life-threatening. tell your doctor if you have heart or blood vessel problems, or develop new or worse symptoms. get medical help right away if you have symptoms of a heart attack or stroke.

most common side effect is nausea. it's me in control now.

when i was one year old, i was diagnosed with a rare form of cancer on my spinal chord. but i spent my whole life fighting back. so you can imagine what i thought when i saw donald trump say... "i don't know what i said, ah, i don't remember!" "that reporter he is talking about suffers from a chronic condition that impairs movement of his arms." i don't want a president who makes fun of me. i want a president who inspires me, and that's not donald trump.

you're watching "nightline." honored. winner of three emmy awards for excellence. good choice. finally tonight, it's been almost four months since that horrific mass shooting at the orlando pulse nightclub. 49 people were killed, 53 others wounded. now the last remaining patient who survived is finally getting

coanchor juju chang. >> your back hurt? >> reporter: juan jose was shot four times at the pulse nightclub in orlando. in his legs, his arm, his back. the shot in his back severely damaged his spinal cord. he is paralyzed from the waist down. [ speaking foreign language ] after 114 days in this hospital, over half of which he spent in a drug-induced coma, he reached a milestone. juan became the last remaining pulse patient to be released. >> thank you. >> take care, okay? >> reporter: today he continues his recovery at a rehab center doing intensive physical therapy. so much closer to finally coming home. >> way to go, juan.

family, and the power of love. he had all three. first corinthians puts it this way. love is patient, love is kind, it always protects, always trusts, always hopes, always endures. thank you for watching abc news. as always we're online at abcnews.com and our "nightline" facebook page. good night, america. mystery of the fiat. who was in the car following kim kardashian around paris? exclusive, the notorious pink panther gang, he was in it. what he's saying today about the gang that robbed kim kardashian. >> does it look like the

group? then, the, ismirking skull inside and the photo. >> freaky looking face. then -- >> donald -- >> he says -- >> rudest debate ever. >> the people at zipper. how to fix a stuck what to do if your shoes are too tight. and what if your jeans won't button? what you should do in a fashion emergency. >> wow. now "inside edition" with deborah norville. >> deborah: hello everybody and thank you for joining us. police in paris are investigating the kim kardashian jewelry heist and no doubt they are studying this