Frankie Valli, best known as the front man of The Four Seasons, sits down with legendary musical director/bandleader Paul Shaffer. Over the course of his career, Valli has scored 29 Top 40 hits with The Four Seasons, one Top 40 hit under The Four Seasons' alias 'The Wonder Who?,' and nine Top 40 hits as a solo artist. He was inducted into the Rock and Roll Hall of Fame in 1990 as a member of The Four Seasons and the Vocal Group Hall of Fame in 1999. Shaffer served as David Letterman's musical director, band leader, and sidekick on the entire run of both Late Night with David Letterman (1982-1993) and Late Show with David Letterman (1993-2015). He began his music career in 1972 as the musical director of the Toronto production of "Godspell" before joining the house band of "Saturday Night Live" from 1975-1980.