FROM HOMELESS TO A DREAM: ONE BEAUTY PAGEANT CONTESTANT'S DETERMINATION TO BECOME MISS USA, ON ABC NEWS' "20/20," FRIDAY, JUNE 17

Plus: Behind the Scenes with Infomercial Impresario AJ Khubani And: Twins with a Startling Difference Also: Digital Infidelity

In the cutthroat world of beauty pageants, where competition is fierce and the hint of scandal can cost you your crown, Blair Griffith was hiding something very personal. Last October Blair was crowned Miss Colorado in the Miss USA Pageant - the next shot was at the national title. But before her bags were even packed for the competition, a knock on the door upended her life. Her family, broke, was being evicted. Blair and her mom, Bonita, speak candidly to Elizabeth Vargas about refusing to give up on her dream of becoming Miss USA, and this Sunday she gets her shot at the title. "20/20" airs FRIDAY, JUNE 17 (10:00-11:00 p.m., ET) on the ABC Television Network.

And: Next Big Thing.... "20/20" travels with AJ Khubani, the direct response king of the infomercial empire Telebrands, as his company sets its sights on Chicago in search of the next big thing. Which hopeful inventor's product will pass the Khubani test? Will he bankroll someone's dream? "20/20" is there to see the master in action. Deborah Roberts reports.

Also: How many people can say they're the only one of something in the world? Jay Schadler reports on twins with a startling difference: Sienna "Sinny" Bernal is an 11-year-old primordial dwarf, yet her twin sister, Sierra, is not a dwarf. They're the only twins known in the world to have such a combination.

Plus: It took just days for the once private activities of a politician to give way to a very public scandal. And this week the pressure mounted from Anthony Weiner's colleagues - even the president - for him to resign. But outside the public spotlight, there's a more serious discussion going on in the homes of average American couples. In this new landscape of Twitter and texting, how do you define infidelity on the internet? Does Anthony Weiner's sexting amount to cheating? What kind of secrets is your spouse keeping from you? "20/20" talks to relationship experts, as well as to couples who have dealt with cyber-cheating.

"20/20" is anchored by Elizabeth Vargas and Chris Cuomo. David Sloan is executive producer.