A subject has to be fairly extraordinary to sustain a reader's interest for a book-length critical study. Luckily, the late R&B singer Marvin Gaye -- a wildly talented, hugely conflicted individual -- fits the bill as the topic of Mercy, Mercy Me. Of course, a fast-paced, controversy-filled life alone does not ensure a good read; that's where the writer comes in. University of Pennsylvania prof Dyson (''Race Rules'') fell under Gaye's spell as a boy and devoted years of his life to unraveling the star's mysteries. The result is a fascinating consideration of Gaye's life, art, sexuality, and musical legacy that yields fresh insights and revelatory ideas on nearly every page (check out Dyson's thoughts on the erotic predilections allegedly shared by Gaye and R. Kelly). Anyone who's ever wondered what was really going on with Marvin will devour this book.