Guest host: Tracy Smith. In our cover story, Lee Cowan attends the Merrie Monarch Festival in Hawaii, the “Olympics of hula.” Also: Jane Pauley talks with Prince Harry and Meghan Markle about their new initiative to help families whose children suffered from online harm; Lesley Stahl sits down with former House Speaker Nancy Pelosi, author of the new book “The Art of Power”; Martha Teichner talks with Philippe Petit, who walked a high wire between the Twin Towers 50 years ago; Seth Doane examines the ramifications of the prisoner swap that freed 16 American political prisoners held in Russia; John Dickerson looks back at the resignation of President Richard Nixon in August 1974; and Kelefa Sanneh profiles rapper-turned-country singer Jelly Roll.