"The Beast" – Scott Pelley reports on the new science of superstorms. What spawned one of the most devastating swarms of tornadoes ever to tear through the United States? Pelley reports from Kentucky, where more than 70 people were killed last weekend and billions of dollars in losses occurred. America's Dirty Secret – Bill Whitaker reports from Alabama's Black Belt, ground zero in an unseen public health epidemic: by some estimates, half the impoverished, rural residents in Lowndes County have raw sewage spilling into their yards and even their homes. Sanitary wastewater disposal is required by the state but not provided to residents outside small towns, leaving many living in the countryside who can't afford it with no sewage systems at all. Whitaker speaks with families battling conditions you'd never expect to see in the heart of America and meets one advocate who hopes to expose what she calls "America's dirty secret." Trevor Noah – Trevor Noah is an unstoppable comedic force. As host of "The Daily Show," he has attracted widespread and sometimes viral attention for his heartfelt and cutting social commentary. Forbes ranked him the fourth-highest-earning comedian, and Time named him one of its 100 most influential people. Lesley Stahl interviews Noah, currently on the road with his latest comedy tour.