tonight on "nightline," guardian agent. for americans fighting to save their homes from foreclosure, he is a real estate godsend. an expert, getting banks to back off. about tonight, we show you how he does it. one tough mudder. it is the sadistic sprint, part mud run, part ice bath, with a dash of e leg tris shock. so, why are thousands lining up and paying big to suffer? and, in search of harmony. for those bathroom mirror sol lowist who dream of belting out hits alongside kelly clarkson and john legend, one reality show is making it a little bit more possible. tonight, a trip behind the scenes of "duets."

>> announcer: from the global resources of abc news, with terry moran, cynthia mcfadden and bill weir in new york city, this is "nightline," july 4th, 2012. >> good evening, i am bill weir. well, as the independence day holiday winds down, we begin with a few rays of hope in the american housing market. home sales are rising, foreclosures are dropping to levels not seen since the crisis hit back in '08. but there are still hundreds of thousands of families locked in a struggle to keep their homes and tonight, we meet a man using his insider knowledge of the banking industry to help even that fight. here's abc's chris cuomo with an encore "realty check." >> i think they're hoping i'm just going to be like, okay, you can have my house. this is my home. i'm not leaving. >> reporter: heather cadman bought her massachusetts home eight years ago. right now, she's fighting the

bank to keep it. a date has been set to auction it off. >> when i heard people were losing jobs and what not in this economy that i knew i could squeak by. but unfortunately, that wasn't the case. >> reporter: heather's a single mom with a 14-year-old son named donny. >> leave it. >> reporter: she also takes care of her 80-year-old mother. >> it's not that i want to stay home and have a free house. i want to work. >> reporter: you're not running away from your debt. >> no, i want to pay my bills. i want a payment that i can afford. i want to pay my mortgage. did you have a good day? good to see you, hon. >> reporter: heather was laid off from a full time job. her new part-time job, even with help from her mother and ex-husband, isn't enough to make ends meet. >> i was just squeaking by. i'd pay on the 15th, you know,

and then it turned into the 16th and then the 17th and then it would be, like, the 29th. >> reporter: so, heather asked her bank, gmac, to modify her mortgage, which sent cost about $2,600 a month. >> i would say, listen, we can resolve this. why don't you guys just drop my interest rate, this is a no-brainer. >> reporter: but the bank's response, she says, was a barrage of letters and collection calls. >> i mean, i'm a hard-working, single mother, taking care of my 80-year-old mother and i'm just trying to get by. and survive. i want to thrive. i'm sick of just surviving. i want to thrive. >> reporter: and they can help you do that. >> they can. by just doing what needs to be done to modify my mortgage. because i'll be able to afford it. i don't know why they don't want to help me. >> you're broke, aren't you? >> reporter: there's no george baileys left in the world. >> it's a loan. it's my business. >> reporter: but maybe there

are. meet bruce. a man with a gift for getting mortgages modified. >> americans own their homes. this is my spot on earth. i've done everything right. this is being threatened. >> reporter: the 54-year-old doesn't look like george bailey. but he knows banks. he's actually a former management consultant who worked in finance. now, from his cramped offices above a pool hall, bruce fights all day against the biggest banks. >> you anticipate this payment would stay about the -- >> hey, how are you? >> reporter: and stays home for people like heather. bruce has been fighting heather's bank to modify her loan eight months now. >> you get to the point where i can say, the mortgage has been changed. it's filed. those are -- >> reporter: and bruce says he can appreciate heaven, because he lived through hell. though he's a savvy businessman, he was once laid off and nearly

lost his own home. >> i've been through this. i know what these people are going through. >> reporter: he figured if it could happen to him, it could happen to anyone. so, bruce decided to help others get their homes back. >> i can't sit here and not help these people. it would be like walking away from somebody in an accident. >> reporter: his hsi trust home savers has taken over 200 cases since he startled it in 2009. and bruce says he's gotten a good outcome in almost all of them. >> these are the folks that worked, saved, put their money into their homes, borrowed against their pension to get their homes. they are the american dream. >> reporter: home savers doesn't work for free. bruce uses a sliding scale, allowing people to pay what they can. >> hi, heather. >> hi, how are you? >> reporter: working together with people like heather, bruce can accomplish big things. remember that auction date? bruce made some calls, talked the talk and voila --

>> luckily, you know, bruce worked his magic and we got it pushed to february 2nd. >> reporter: and now that battle they've been fighting may be coming to a happy close. so far, heather's monthly payment has been reduced from about $2,600 to just under $1,700. and after we called gmac, they agreed to postpone heather's auction date until march. in a statement, they say they are committed to working with borrowers like heather. >> i live in this country, i have a home and i want to live the dream, you know, that's all i want to do, i want to live the dream. >> and we are happy to report that since chris filed that report, heather cadman received her permanent loan modification this summer. well, coming up next, it is the brutal, dirty, long distance race that is designed to hurt you. so, why are thousands signing up? ♪ [ male announcer ] this is our beach.

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>> announcer: "nightline" continues from new york city with bill weir. >> they claim it is probably the toughest event on the planet, end quote. they, being the organizers of the tough mudder, a masochistic endurance competition that's exploded in global popularity in inspite or maybe because of it. one of our colleagues stepped forward to see if he had what it takes and in an encore performance, here's abc's matt gutman. >> reporter: a what? a mudder. definition. a person who pays to crawl through and be encrusted in and sometimes flip into mud. a tough one, but a person that does it over 12 1/2 miles,

through electrified wire and what seems to be torture devices. perhaps the toughest mudder? you got blown up, ied, when you woke up, you were surprised your leg was still there? >> yeah. >> reporter: and then you asked for it to be amputated. why would you do that? >> why would i have a bum leg? i'd be walking with a cane. pretty much worthless. >> reporter: ben lunak lost his leg in iraq in 2005. he hasn't looked back, climbing kilimanjaro last year and now, attempting this, along with 6,000 other runners near phoenix, arizona. it's just one of 35 tough mudder events this year, one of the fastest growing businesses in america, going from 50,000 participants in 2010 to a projected 500,000 in 2012. and so, every tough mudder begins with a preemptive pledge

to suck it up. >> three, two, one! >> reporter: i love it! i love it. why would anybody do this? >> you know, people want to prove something to themselves. for everyone, it's a different reason. not that they're bored with conventional fitness, that they're sitting at their office job and nothing's actually scared them since they were about 9 years old. >> reporter: alex patterson is tough mudder's marketing chief. he comes up with names like arctic enema and funky momonkey. a harvard grad with a law degree, his job is partly to conjure up these obstacles and partly to ensure the company doesn't get sued for that. what's in store next? >> what's in store next is the arctic enema. it's a dumpster full of ice wat water, it's absolutely freezing. the mother of all ice cream headaches.

a >> reporter: it was pretty cold. i don't want to tell you about my nether regions. take me with you! i was joking, kind of. at 150 bucks a ticket, the company may be the pacemaker, but the entire challenge industry is grabbing america by the -- jock strap. one of the reasons for its success is camaraderie. quickly, ben was becoming an inspiration to the other runners. >> keep going! >> reporter: twinkle tolls was the only obstacle he thought he'd fail. >> keep moving! >> reporter: but the miles and the pain begin to pile up. this can't just be less than halfway. >> well, it's 12 1/2 miles, so, that's the six-mile mark, yep. >> reporter: ben's prosthesis fills with mud. if you are a mudder, you now start to have fun. >> let me wash my face.

>> reporter: the obstacles are absurd. a smorgasbord of pain. this is called "walk the plank." the water, frigid and deep. divers are there to ensure nobody drowns. serious business, where no one seems to take themselves too seriously. by now, ben's prot tee sis is so clogged with mud, he can barely walk. we were sure he'd make it through. now, not so much. by the time we reach this doomsday machine, my teeth are chattering uncontrollably. life was about to get much worse. >> now we have 10,000 volts of electricity. people say, is that legal in america? well, at least right now it is. >> reporter: first, ben goes through, flag in hand. not only do we get shocked, but ben and i are knocked out cold, falling face first in the hud.

you try to get up, bang, zinged again. lights out. that was insane. i blacked out several times. you were talking to me, someone was talking to me, i was flat out in the mud, i woke up in the mud. that was so cool. traditional tough mudder beer in hand, we toasted ourselves and the toughest mudder. another bunch of muddy, freezing but satisfied customers. for "nightline," i'm matt gutman in phoenix, arizona. >> at least he gets the cool head band. thanks to matt. and coming up next, a new reality show where pop stars like kelly clarkson come out from behind the judge's table and onto the stage. that's next. time out. sweet. [ female announcer ] with charmin ultra soft, you can get that cushiony feeling you love while still using less.

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it is not your typical musical reality show. in this version, chart toppers like kelly clarkson and john legend are taking the stage alongside the contestants and banking on the idea that two voices are better than one. here's abc's gloria riviera. ♪ you got me begging you for mercy ♪ >> reporter: we might not admit it, but everyone loves a good duet. and everyone has a favorite. ♪ ain't no mountain high enough ♪ >> marvin gaye and tammy, they just had a certain -- >> mariah whitney. because i'm a girl. >> reporter: so, what exactly makes a great one? the reality show "duets" is

asking american to figure it out. >> i heard a couple of pitchy things here or there. >> reporter: but we have never seen this. ♪ some people want diamond rings ♪ >> reporter: judges singing on stage, helping their proteges compete. and behind the scenes, too, helping with singing and song selection, even fine-tuning dance moves. >> what doesn ♪ what doesn't kill you >> reporter: kelly clarkson. robin thicke. ♪ this ain't a movie >> reporter: r & b star john legend. and country rocker jennifer nettles of sugarland, compete each week with their own hand-picked partner. the show is hoping that unlocking the mystery of a great duet will unveil a single star. ♪ i'm begging you >> do something cute. >> reporter: kelly clarkson is one of them. she won the original "american idol" in 2002 and she knows a thing or two about pressure and

critics. >> this wasn't your greatest performance for me. >> ten years later and i love, like, finding, you know, kids that were my age when i started. i had no guidance. ten years later, giving that to somebody was kind of a cool idea for me. >> reporter: jennifer nettles and her partners are dominating. landing at the top of the chart each week. >> y'all are both going to win and then we're going to do a new show and call it "trios." >> it's crazy amazing. i didn't know what it was going to be like, but the first note we sang, i'm like, oh, my god. i'm like, this may be some money here. >> reporter: but sharing the spotlight isn't always easy. >> i don't want to share the stage with anyone. i don't even like having dancers around. i want all eyes on me, baby. >> reporter: actually, it's robin who reveals the first surprising hint at what makes for a great duet. >> it's not about singing with perfect pitch or trimming, it's about feeling. all art is supposed to create

feeling, you know? and if you sing with passion and sing from the soul, then people will feel it. >> reporter: i wonder if the show is cheating. wouldn't anyone sound great alongside these stars? >> a little bit of "silent night." ♪ silent night ♪ holy night ♪ all is calm >> reporter: we struggle at first, but then, we sort of hit our stride. ♪ sleep in heavenly peace >> i get to the end. >> reporter: suddenly, i see how singing with a star could really raise your game. >> the voice is so smooth and his technique and i'm just trying to get like him. >> reporter: the very best duets sound seamless. artists call it blending, when the tone of two voices come together at one. >> it's like a basketball team. certain players have certain strengths and certain weaknesses and you try to, through playing together, you figure these things out. >> reporter: if you were to join in, can you do this?

♪ everywhere i'm looking now ♪ i'm surrounded by your embrace ♪ ♪ baby i can see your halo ♪ i pray it won't fade away >> reporter: i have the chills. ♪ i pray it won't fade away >> reporter: and that may be the best sign of what makes a great duet. for "nightline," gloria riviera, los angeles. >> thanks, gloria. thank you for watching abc news. we do hope you check in on "gma." we're always online at abcnews.com. >> jimmy: sgrk is coming up next, but before we go, the sights and sounds of america's birthday party at the national mall in washington, d.c. have a great remainder of this holiday and we'll see you back here tomorrow. ♪