Plot: In our cover story, Tracy Smith scares up a report on nightmares and how to face our fears. Also: Norah O'Donnell interviews longtime Hillary Clinton aide Huma Abedin; Seth Doane reports on the return of the Swedish pop group ABBA; Lee Cowan meets a photographer who captures kids' inner superheroes; David Pogue witnesses true card magic with illusionist Shin Lim; Luke Burbank sits down with actor Kal Penn; and Martha Teichner tags along with a photographer who takes haunting portraits of abandoned houses - time capsules of the departed