In the spring of 2018, David Letterman walked into Shangri-La, Rick Rubin’s studio in Malibu, for a segment on his Netflix show, My Next Guest Needs No Introduction. Rubin famously has made records with Johnny Cash, Adele, the Beastie Boys and Jay-Z. The person he wanted Letterman to hear that day was a 23-year-old who, not long before, had been planning to play professional volleyball overseas. Her name was Madison Ryann Ward, and she was recor…