Wade Mainer helped invent the two-finger banjo style that bridged old-time mountain music and bluegrass, played the White House for Franklin Roosevelt, and then, at the height of his fame, packed his banjo away and took a job on a General Motors assembly line in Flint, Michigan. He lived to be 104.

This episode follows him from a log cabin in the Blue Ridge Mountains of North Carolina, where he practiced on other musicians' banjos during square dance breaks, to radio stardom sponsored by Crazy Water Crystals, a $5-a-week music paycheck he left for a $15 mill job, the Sons of the Mountaineers and more than 165 sides for RCA Victor, his marriage to Julia Mae Brown, known as Hillbilly Lily, his wartime decision to ground the band, a religious awakening, and a late return to gospel banjo.

• How two-finger picking differs from clawhamme ...