At the heart of every great show-business career is an enigma. No matter how manifest a performer's talent, no matter how assiduously he courts his fans, there remains a puzzlement: In a fragmented and fickle world, what accounts for enormous, enduring popularity?
Among postwar American entertainers, none provoked that question more often than a kitsch pianist with a scullery maid's idea of a regal wardrobe, who for more than 40 years attracted stalwart Middle Americans to romps that he himself once characterized as "just that far away from drag." As a musician, Liberace was a panderer: he edited classics down to...