>> hi. i'm thuy vu, and i'd like to welcome to you this special presentation of the award-winning documentary "the power of two." it's a powerful look into the lives of twin sisters born with cystic fibrosis and their struggle to fight this often fatal genetic disease. their inspiring story is next, and later in the broadcast, they'll join us in the studio to talk about the film, their journey, and how you can help, and now "the power of two."